88 DEAN. [Vous LEX. 
given by Traquair!4 pertained to Cladodus, Newberry was 
somewhat in doubt. Traquair had ascribed to a shark whose 
teeth were of the mzrabzlis type, a pectoral fin whose form was 
a ‘‘monoserial archipterygium intermediate between the truly 
biserial one of Pleuracanthus and that of the modern shark.” 
The writer, basing his observations upon recently discovered 
material, must, however, follow a suggestion of Smith 
Woodward as to important differences in fin structure, and 
regard the shark of the Waverly as entirely distinct from 
the Cladodus of Traquair. Accordingly he regards it neces- 
sary to distinguish the American form, and would suggest a 
new genus, Cladoselache. 
The material from which this shark type has been studied is 
in the possession of the museum of Columbia College. It 
includes the types of Newberry, a number of specimens hitherto 
undescribed, together with a most interesting and well- 
preserved example of C. jfylevt, recently acquired.’ This 
specimen is one of an admirable series that Dr. Kepler has 
succeeded in discovering at Linton, and is the first which has 
been known to exhibit the tail structure. 
At the present time it is possible to consider more exactly the 
structural characters of this generalized shark type, and they 
prove of no little interest from a morphological standpoint. 
The evidence they present as to the orign of paired limbs 
Smith Woodward 9 has lately commented upon, regarding their 
fin structure as the least modified of known forms in which the 
lateral fold has become divided into its two elements. On the 
other hand there may be considered in some detail the objections 
recently urged by Jaekel!2 as to primitive characters. This 
author, for example, would consider the fin structure as of 
essentially a modern type, ray-like in its specialization to 
bottom living, in no way, therefore, strengthening the lateral 
fold doctrine. He assumes, moreover, that the entire posterior 
portion of the body in the type specimens, which he as well as 
Smith Woodward had examined in the museum of Columbia 
College, had been falsely added; although he admits that the 
presence of circumorbital derm plates is of especial interest 
phylogenetically (Acanthodian). 
