G. It. Eastman — Neio Elasmobranchs from Solenhofen. 401 



specimen in the Carnegie Museum from the same horizon and 

 locality, immediately to be described as the type of a new 

 species ; and it seems proper to associate under the latter head 

 the small shark which the late Geheimrath von Zittel regarded 

 as the young of C. falcifer. 



Cestracion zitteli, sp. nov. 

 (Plate I.) 



The example which is here regarded as typical of a distinct 

 species merits special attention on account of its being proba- 

 bly the most perfect post-Liassic Cestraciont shark which has 

 thus far been discovered in the fossil state. Agreeing in prin- 

 cipal characteristics with the small form described by von Zit- 

 tel as the young of G. falcifer, as above stated, its features are 

 nevertheless judged to be sufficiently distinctive as to warrant 

 a separation from that species. 



The more important differences relate to the position of the 

 dorsal fins, form and relative size of the dorsal fin-spines, num- 

 ber and size of the vertebral centra, and presence of a series of 

 enlarged radially ridged and acutely conical shagreen tuber- 

 cles along the back. A comparison of characters displayed by 

 the dentition in the type specimen of G. falcifer is impossible, 

 as the teeth are unfortunately not preserved, but in the small 

 Munich example, which may be with entire propriety associ- 

 ated with the type now under description, the latei*al teeth are 

 said to be "mit eine Anzahl von Zacken versehen." This 

 statement may be understood to mean that the oral snrface is 

 faintly rugose, transversely striated perhaps, or else that the 

 coronal margin- is slightly indented. In any case, however, 

 the teeth must have been exceedingly minute. 



A summary of the chief features of interest presented by 

 the type specimen may be given as follows : Form of body 

 slender and elongate, total length from extremity of snout to 

 that of the vertebral column about 15 cin . Vertebral centra 

 varying somewhat in length, being more compressed in a longi- 

 tudinal direction underneath the second dorsal fin. About 25 

 centra occupy the interval between the bases of the two dorsal 

 fin-spines, and it is noteworthy that these latter abut almost 

 directly against the column, as if they had been deeply implanted 

 in the flesh. The spines themselves are of relatively large size, 

 smooth, sharply pointed distally, and only slightly arcuate or 

 recurved. 



Portions of the fin-membrane or shagreen covering of the pec- 

 toral pair, as well as the greater part of the pelvic, anal, and 

 caudal fins, are preserved. The anal is nearly opposite the pos- 



