Description
Original diagnose after Eastman (1911) p. 401-402 [752]: The example which is here regarded as typical of a distinct species merits special attention on account of its being probably the most perfect post-Liassic Cestraciont shark which has thus far been discovered in the fossil state. Agreeing in principal characteristics with the small form described by von Zittel as the young of C. 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, number and size of the vertebral centra, and presence of a series of enlarged radially ridged and acutely conical shagreen tubercles along the back. A comparison of characters displayed by the dentition in the type specimen of C. falcifer is impossible, as the teeth are unfortunately not preserved, but in the small Munich example, which may be with entire propriety associated with the type now under description, the lateral 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 cm . Vertebral centra varying somewhat in length, being more compressed in a longitudinal 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 pectoral pair, as well as the greater part of the pelvic, anal, and caudal fins, are preserved. The anal is nearly opposite the posterior dorsal and, except for being more sharply pointed, resembles it in form and proportions. The pelvic pair is decidedly acuminate, and placed midway between the anal and pectoral pair. The pelvics slightly exceed the second dorsal in size, which latter is somewhat higher and longer than the first dorsal ; and the depth of the pectorals is about one-third greater than that of the pelvic pair. Nearly the entire front margin of the right pectoral fin is preserved, but the distal portion of the left pectoral is either concealed or broken away. The same is true of the terminal part of both lobes of the caudal. The general outline of body and position of all the fins is shown in the accompanying illustration (Plate I). In this the shaded area immediately behind the head indicates a piece broken away from the containing rock. The specific name is bestowed in honor of the memory of the late and deeply lamented Geheimrath Karl von Zittel, of Munich.

Remarks
shark-references Species-ID=2817;

References