REPORT OF TEE CHIEF ASTRONOMER 809 



SESSIONAL PAPER No. 25a 



250 _ 



^=-. Ulmus protoracemosa, n. sp. 



Plates IV-VI. 



This plant is represented by a single specimen of calcined wood, the structure 

 of which is fairly well preserved, chiefly with respect to the transverse section. 

 In the longitudinal sections the structure is so altered that many of the essential 

 details cannot be determined, and the final diagnosis must be deferred until 

 such time as more ample and more perfectly preserved material renders it possible 

 to draw it accurately. The provisional diagnosis nevertheless shows this wood 

 to be that of an elm. While the wood of this genus is not known in horizons 

 earlier than the Pleistocene, in which formation both U. americana and TJ. 

 racemosa are well recognized types, the present material affords the first definite 

 knowledge of the woody structure of a genus in formations where its leave3 

 have been known for some time. Among existing species this wood is probably 

 most nearly comparable with U. racemosa — a species which exhibits great struc- 

 tural variation along lines essentially parallel with those shown in the present 

 case. Prom the details of structure available, it is perhaps not unsafe to assert 

 that the resemblance is so close as to justify regarding the fossil as the prototype 

 of that species, and it is therefore named with reference to this fact. The diag- 

 nosis so far as obtained is as follows : — 



Ulmus protoracemosa, n. sp. 



Transverse. — Growth rings very variable and with no obvious distinction of spring 

 and summer wood; in stems of rapid growth very broad and showing 

 a gradation of vessels and wood parenchyma; in stems of slow growth 

 very narrow and more variable. Structure rather dense in the 

 greater portion of the ring; the wood cells medium, rather thick- 

 walled. Vessels of the spring wood medium, not very large, radially 

 oval or oblong and often so disposed as to be radially 2 seriate but 

 without thyloses; forming about £-4 the thickness of the ring and 

 abruptly replaced by small vessels and wood parenchyma forming 

 small to medium tracts which are more or less distant and constantly 

 diminishing in size outwardly, sometimes forming diagonal or even 

 tangential series, the contained vessels often lying in radial series of 

 2-4. Medullary rays poorly denned but rather numerous and several 

 cells wide. 



Radial. — Medullary ray cells all of one kind, straight, rather thin-walled with no 

 recognizable markings. Vessels short and broad, the radial walls 

 with multiseriate and chiefly hexagonal, bordered pits. 



Tangential. — Rays numerous, low and broad, upwards of 4 cells wide and never 

 uniseriate. Vessels as in the radial section. 



250 



—— of 1905. Ulmus protoamericana, n. sp. 



G 



Plate VII. 



250 

 The specimens designated as — - represent another species of Ulmus in a 



Gr 



very perfect state of preservation which permits of drawing a diagnosis with 

 completeness. Whatever doubts may attach to the preceding species with respect 



