librium a little more quickly. Considerable judgment must be exercised in its use however.

Finally the effect of the stirring system was investigated and it was found that running at normal speed, the fans gave a rise in temperature of about .1° per hour; so that any slight variation in speed of fans is not important, but great variations may interfere with close regulation.

The ease with which one temperature after another can be obtained is one of the features of the apparatus. Other advantages are the wide range of available temperatures, the precision with which any given temperature may be reached and maintained, the large volume of heating chamber, ease of observation and the certainty of operation. Another advantage in work near the critical point is the small amount of damage caused by explosion. The windows, which are easily replaced, may be blown out but no injury to the essential parts has ever occurred and explosions have not been infrequeat.

QUEEN'S UNIVERSITY,

KINGSTON, ONTARIO.

Proceedings of the American Academy of Arts and Sciences.

VOL. XLVIII. No. 16. MARCH, 1913.

CONTRIBUTIONS FROM THE PHANEROGAMIC LABORATORIES OF HARVARD UNIVERSITY.- No. 59.

CRETACEOUS PITYOXYLA FROM CLIFFWOOD, NEW

JERSEY.

BY RUTH HOLDEN.

WITH FOUR PLATES.

CONTRIBUTIONS FROM THE PHANEROGAMIC LABORATORIES

OF HARVARD UNIVERSITY. — No. 59.

CRETACEOUS PITYOXYLA FROM CLIFFWOOD, NEW

JERSEY.

BY RUTH HOLDEN.

Presented by E. C. Jeffrey. Received December 1, 1912.

DURING the spring of several successive years, Dr. E. C. Jeffrey collected a considerable amount of lignite from the Middle Cretaceous of Cliffwood, New Jersey, which he has since turned over to the writer for investigation. The material was from two localities, that from the yards of the Cliffwood Brick Company, and that from Cliffwood Beach. The former lot was as a whole badly pyritized and of no value from a structural standpoint; while the latter was often perfectly preserved, revealing all the details of its structure under microscopical examination. The greater part was found to belong to the genera Cupressinoxylon, Araucarioxylon, and Brachyoxylon, and will be described later. There were also specimens representing three types of Pityoxylon; the characteristics and affinities of which it is the purpose of this paper to discuss.

Pinus protoscleropitys n. sp.

It will be appropriate to begin with the one which most closely resembles modern forms. Figures a, c, and e, Plate 1, reveal the general features of the lignite in question. It will be noticed that the tracheides are small and thick walled. The summer elements are few in number, but limit a well marked annual ring, as shown in the lower part of Figure a. Resin ducts such as are characteristic of all Pityoxyla occur in two planes. Figure a includes two vertical canals, and to the right a horizontal one. It is apparent that both are completely filled with tyloses,— a condition more clearly seen in Figures Surrounding each, there is a jacket of epithelial parenchyma. The cells composing this jacket are thin walled, heavily pitted, and in general devoid of contents. Figure d, on the other hand, illustrates a case where they are filled with a dark, resinous substance. Figure b gives the topography next the pith,- at a lower magnification. It will be noticed that, as in the hard pines, there is a double series of

and e.