the name of the Perch-pest,1 of a singular animal belonging to the Lerneans, whose history has been given by Dr. Nordmann, and which is distinguished by a sucker common to two legs. Several other Lerneans have similar suckers." Amongst insects are a variety of animals which are known to walk against gravity, we see the common flies, and other twowinged and four-winged insects, walk with ease upon the glass of our windows, and course each other over the ceilings of our apartments, without, in either case, falling from their lubricous, or seemingly perilous station. Writers on the subject are not agreed as to the means by which this is effected, some supposing that it is by atmospheric pressure, produced by suckers; while others maintain that it is by a thick-set brush, composed of short bristles, on the underside of the foot, or by certain appendages at the apex of the claw joint of that organ. Probably both these causes are in action, for though the pulvilli or foot-cushions of flies may adhere by mechanical means, those of some Hymenopetra and Orthoptera seem evidently furnished with suckers. In both cases the design of an Intelligent Cause is apparent; His wisdom, which, under different circumstances, contrives different means to attain the same end; His power, which gives effect to that purpose and contrivance; and His goodness, which causes every varied mean to subserve to the more convenience and comfort of the animals in which each obtains. Could we trace exactly the history and habits of every group of animals, nay, of each individual species, we should discover that the slightest variation was to answer a particular end; and that even its very hairs and pores were all numbered with reference to special uses, foreseen by Divine Wisdom. Amongst other purposes for which suckers were given to the Class of Insects, one bears relation to the intercourse of the sexes. This is particularly observable in the males of the predaceous beetles, especially the aquatic ones. In the terrestrial ones? indeed something of the kind takes place, for the males may be known by having the three or four first joints sometimes only of the anterior tarsi, and sometimes of the intermediate, more or less dilated and furnished underneath with short bristles, intermixed, it should seem, with very minute 1 See above, pp. 200, 205. 2 See Nordmann, t. vii. viii. 3 Philos. Trans. 1816. 322. t. xviii. Introd. to Ent. ii. 322. White's Selborne, ii. 274. Ed. Markw. 4 5 6 Blackwall in Linn. Trans. xvi. 487. 7 Cicindelidæ, Harpalidæ, Carabidæ, &c. suckers, and in some with transverse ones.1 But these organs are most conspicuous in the male of our most common waterbeetles, in which the three first joints of the anterior tarsus form a dilated orbicular shield, covered with minute suckers, sitting on a tubular-foot-stalk, with two exceeding the rest greatly in size. The intermediate legs also have the three first joints thickly set with minute suckers. Leaving the invertebrated animals the occurrence of suckers becomes very rare; very few instances are upon record, in the whole Sub-kingdom of vertebrated animals, of this kind of formation, two, in the Class of fishes and the other in that of reptiles, namely the lump-fishes, the sucking-fishes, and the Gecko lizards. Under the name of lump-fishes I include all those whose ventral fins unite to form a disk or sucker by which they are enabled to adhere to the rocks, constituting Cuvier's family of Discoboles. But the most celebrated of this tribe, in ancient as well as modern times, are the sucking-fishes or Echeneis which Pliny says were so called from their impeding the course of the vessels to which they adhered. On the back of their head they have an oval cotyloid disk fitted with numerous transverse lamina denticulated at their posterior edge, forming a double series; by the aid of this apparatus, which appears to adhere by means of the teeth of its lamina as well as by suc tion, this animal attaches itself to the whale, the dolphin, the shark, the turtle, and other inhabitants of the waters, and even to vessels, that are sailing, and thus organs, which at first sight appear to stop all locomotion in the animal, are the means which enable it, like certain barnacles, to traverse half the globe. The fins of this animal do not permit it to swim with ease and velocity; and therefore this must be regarded as a compensating contrivance, by which it can the more readily fulfil its functions and instincts. Though they are disengaged with difficulty by human force from the vessel to which they are fixed, they very easily detach themselves, and swimming on their back, pursue any object that attracts their attention or excites their cupidity. It is singular to remark that in the case of two such animals, as the barnacle amongst the Cirripedes, which has naturally no locomotive powers and organs; and the Echeneis amongst the fishes, in which they are insufficient to transport it far from 1 E. G. Harpalus caliginosus. F. 2 Dytictus marginalis, &c. Philos. Trans. ubi supr. t. xx. 3 Cyclopterus Lumpus, &c. 5 Gecko. Daud. Stellio. Schn. Ascalabotes. Cuv. 4 Echeneis. 6 See above, p. 191. its native rocks and haunts, such means should be afforded by a kind Providence of visiting in safety the most distant oceans. These animals, though they may be called parasitic from their adhering to other animals, yet as they do not appear to imbibe any nutriment from them, the design of this singular instinct seems to be merely their transport, for purposes not yet fully ascertained. But there are other fishes whose mouth is a suctorious organ, analogous to that of the leech, by which they suck the blood of the aquatic animals they adhere to; of this description are the Lamprey and the Hag, but upon these I shall not further enlarge. The other sucker-bearing vertebrated animals which I mentioned, were those Saurians which form the genus Gecko, and the object of this structure, in them, is to enable them to walk against gravity, that thus they may be empowered to pursue the insects, possessing the same faculty, up perpendicular or along prone surfaces. These suckers. consisting of transverse lamina occupy the terminal part of the underside of the toes. By aid of these organs they can mount the smooth chunam walls of houses in India. Another Saurian genus, the Gecko, of the West Indies, has a similar organ, by means of which it climbs up trees, as well as the walls of houses, in the pursuit of insects. The adhesion of suckers and their relaxation, especially in locomotion, in order to answer the end for which they were given, must be as perfectly dependent upon the will of the animal, as our steps on the plane we are moving on are upon ours; and yet in some instances, as in the perch-pest," the animal, when once fixed, can scarcely disengage itself; but in this case, having attained its ultimate station, this is of no importance. If we study the individual cases of all the sucker-bearing animals, we shall find that this kind of organ was necessary, and all its modifications, to enable them to fulfil effectually their several instincts, and to do the work appointed them by their allwise Creator. For instance, in vain would the Cephalopods pursue and endeavour to seize and devour the crab or the lobster, if, instead of tentacles set with numerous suckers, they had the paws and retractile claws of the Feline race or how would the Gecko be enabled to overtake its insect provender, if its feet were like those of the rest of its class? 1 Petromyzon. 3 Philos. Trans. 1816. t. xvii. f. 2. 5 Achtheres Percarum. See above p. 252. 2 Myxine, 4 Anolius. As supplementary to this account of suckers, I may mention a locomotive organ, given to a very numerous tribe of invertebrated animals, which, as I observed on a former occasion, ap pears in some degree to partake of the nature of a sucker, and which is eminently adapted to the structure, circumstances, and wants of the animals that are provided with it. I mean the expansile foot of the great majority of Molluscans: these animals are the only instance of a unipede structure in creation, but this one foot answers every purpose of a hand or leg; it spins for the bivalves their byssus, is used by others as an auger, by others as a trowel, and by others for other manipulations, and is generally their sole organ of locomotion; from its soft and flexible substance it can adapt itself to the surfaces upon which it moves, and by the slime that it copiously secretes lubricates them to facilitate its progress. In very dry weather. however, it cannot move with ease over the arid soil, but when humid from rain, the whole terrestrial Molluscan army issues forth, naked, or in various panoply, each according to its kind, covering the face of the earth, so that it is not easy to avoid crushing them. The most careless observer of God's creatures must be struck by the correspondence between this foot, and the animal to which it is given; had its locomotions been by means of an organ of a solid substance, or by means of several such organs, the harmony of structure which now strikes us, and relationship between its different parts would be done away, and we should think we beheld a mongrel monster engendered by strange mixtures of animals, rather than a creature harmoniously moulded by the hands of an allwise Creator. I may also mention here a few other organs which seem to present some analogy to suckers, and which, though aiding in locomotion, are not, strictly speaking, locomotive organs, or those by which locomotion is effected. I allude to the spurious legs, or prolegs of the larves of insects. These are usually retractile fleshy organs, analogous to the bristle-armed protuberances of the Annelidans, rendered necessary by the length of these animals, and supporting them as props, and which usually, by means of a coronet or semicoronet of hooked spines or claws, and by applying their prone surface to the plane of position, take strong hold of it: these legs do not step: the six anterior jointed legs, where they exist, are the walking legs; but these organs having been fully described in another 1 Sce above p. 135. 2 Ibid. p. 133. 3 Ibid, 156. joint work of Mr. Spence and myself, I must therefore refer the reader for further information on the subject to that work. What are called the pectines or comb-like organs of scorpions, and those pedunculated ones which are attached to the hind legs of the Solpuga or Galeodes, are conjectured by M. Latreille to be connected with the respiration of these animals. Amouroux seems to regard the former as a kind of sucker, but no actual observations have as yet ascertained their real nature, except that the author last named, states that he has seen the animals use them as feet. Sete or Bristles. Having fully considered suckers and their analogues, I shall next advert to a species of locomotive organ, principally confined to the Annelidans, animals whose locomotions are chiefly produced by the contraction and expansion of the rings of which their body is composed, but which are also furnished with lateral sentiform organs, which assist them in their motion, by pushing against the plane of position. The majority of these animals are aquatic, and some of them grow to a great size; I have a specimen, which I purchased from the collection of the late lamented Mr. Guilding, which is more than a foot long, and as thick as the little finger: it has a double series of what may be denominated its legs, each furnished at its extremity with a bunch of very fine retractile bristles, and those of the dorsal series having besides a branchial organ or gill on each side, consisting of numerous threads. This remarkable animal appears to belong to Savigny's genus Pleione, and is probably his P. Pedunculata, and the Nereis gigantea of Linné.. The bristles on these legs seem not calculated for pushing on a solid surface, but are rather organs of natation, analogous, in some degree, to the branching legs of the Branchiopod Entomostracans. In the earth-worms the lateral bristles are simple, and used to assist their motions, either on the surface, or when they emerge from the earth, or make their way into it. At first sight, one would not suppose the bristles of the Anne lidans to be analogues of jointed legs, or preparatory to their appearance in the great plan of creation but when we reflect upon the approach which many of the Nereideans of Savigny make to the Myriapod Condylopes, and that these bristle-bearing legs, in Mr. Guilding's genus Peripatus, begin to asssume the appearance of articulations, and are armed at their apex 1 Introd, to Ent, iii. 134. 3 See above, p. 186, PLATE VIII. FIG. 1, 4. 4 Ibid, FIG. 1. 2 Lumbricus, |