CHEIEOLEPIS. 295 



The description is accompanied by a sketch made by Professor 

 Williamson from a specimen in his collection. 



The two examples shown in Text-figs. 53a and b are, no doubt, 

 identical with the type of Phillips ; the more acute angle at which 

 the small branches are given off can hardly be regarded as a 

 difference of specific importance. This type of Conifer is represented 

 by a single specimen in the British Museum ; those shown in 

 Figs. 53 a and b are from the Scarborough and Whitby Museums 

 respectively. With such fragmentary material it is impossible to 

 construct any satisfactory diagnosis, and in the absence of cones we 

 cannot adduce evidence of a trustworthy character as to the probable 

 relationship of this rare form to recent genera. Such few specimens 

 as have been obtained seem to warrant the separation of this species 

 from Pagiophyllum Williamsoni \ the falcate and stiff leaves bear 

 a fairly close resemblance, on a small scale, to the large leaves of 

 the latter species, but the much smaller size of the vegetative twigs 

 of Cheirolepi8 setosus and the somewhat different habit afford 

 distinctive characters. 



The question of generic designation is not an easy one to decide 

 in dealing with fragmentary branches of fossil Conifers. The 

 twigs of this species have not been found with any trace of cones, 

 and the only characters available are afforded by the habit and 

 the form and arrangement of the leaves. Certain authors have 

 used the genus Brachyphyllum in a wide sense, so as to include 

 branches with sharply pointed, small, and somewhat falcate 

 keeled leaves, as well as branches with closely adpressed broad 

 scale-leaves, such as occur in Brachyphyllum mamillare, Brongn. 

 It is better, however, to restrict this generic designation to fossil 

 Conifers in which the leaves are broad and inserted on the 

 stem by a rhomboidal base, and to include branches with the 

 narrow and more spreading leaves under different generic names. 

 There is the closest resemblance between the specimens repre- 

 sented in Pig. 53 and Brachyphyllum Ifuensteri, as figured by 

 Schenk from beds of Rhaetic age ; * while hesitating to refer the 

 Yorkshire fossils to this species, the agreement of the vegetative 

 characters suggests specific identity. Saporta 2 substitutes the 



1 Schenk (67), pi. xliii. 



2 Sapovta (84), p. 490. 



