CATALOG OF THE FOSSIL FISHES IN THE CARNEGIE MUSEUM. 397 



"Our knowledge of this species has depended hitherto solely upon the type 

 specimen, which lacks the anal and is in other respects incomplete. It must be 

 regarded, therefore, as an extremely fortunate occurrence that a second and more 

 perfect example of this forerunner of modern Dogfishes should have been dis- 

 covered a half-century after the first was found, and should provide the means of 

 further enlightenment concerning this genus and species. 



"The total length of the Carnegie Museum specimen, which bears the catalogue 

 number 4780, is a trifle less than 40 cm. It is a little difficult to determine the 

 exact length of the head, but it was apparently contained between five and six 

 times in the total length. The outline of the cranial roof, including the orbits on 

 either side, and that of the lower jaw, is clearly shown. In the ethmoidal region 

 and elsewhere in the body, the rounded or polygonal tesserae of the endoskeletal 

 cartilage are beautifully displayed, and the same remark applies to the fine shagreen- 

 granules occurring throughout the integument. Just beneath the orbital cavity 

 are to be seen impressions of a few minute teeth, each provided with one principal 

 and a pair of lateral cusps. 



"The vertebral column is preserved intact almost to the extremity of the 

 tail, being flexed upward to support the upper caudal lobe. Ninety-six vertebral 

 centra are to be counted in continuous series, and it is probable that not more than 

 five or six are missing from the posterior extremity. The centra are of the usual 

 hour-glass form, and do not call for any special comment. 



"Both the median and paired fins are very well preserved. The pectorals 

 are large, lappet-like, not abruptly truncated distally as in modern representatives 

 of Scyllium, but obtusely pointed, as is the case in Cretaceous species of Palce- 

 oscyllium. The low pelvic fins arise at a point opposite the middle of the first 

 dorsal. The endoskeletal supports consist of at least a dozen segmented radialia. 

 The first dorsal arises at about the middle of the back, is of triangular form and 

 moderate height, with twelve or more strong radialia. The second dorsal is similar 

 to the first, but smaller, and the gently rounded anal lies directly beneath its 

 posterior half. The tail is strongly heterocercal, in this respect differing from 

 Palceoscyllium and resembling the recent Ginglymostoma. 



"A minor feature which deserves perhaps casual mention is the preservation 

 within the intestinal tract, near the vent, of portions of undigested food, including 

 small ganoid scales, fragments of a small finely striated dorsal fin-spine (doubtless 

 the young of some Cestraciont shark), and a number of small Echinoid spines, 

 besides a few Foraminifera tests."' 



' Eastman, I. c. 



