MARYLAND GEOLOGICAL SURVEY 27 



occiput, above the condyles. It measures, across the transverse pro- 

 cesses, five inches; transverse diameter, three inches; and the ring is 

 about one inch thick. 



Dimensions : 

 Total length of head, from the temporal crest to 



the presumed extremity of the Jaw 17 in. (425 mm.) 



From the anterior borders of the spiracles to the 



presumed extremity of snout 11.5 in. (887.5 mm.) 



Breadth of skull above, across the occipital crests. 5 in. (125 mm.) 



Breadth at base, between the temporal bones 6.5 in. (162.5 mm.) 



Longest diameter of largest tooth at the socket. . 3.5 in. (87.5 mm.)" 



In the Museum of the Academy of Natural Sciences of Philadelphia 

 there is a tray of vertebrae, one of which is labelled in ink T. (Tre- 

 iosphys) pseudogrampus, over this there has evidently been pasted a 

 paper label which is now lost. Three other vertebrae in the same 

 tray bear pasted paper labels Delphinapterus tyrannus. There is a 

 loose label in the tray marked " Delpkinus calvertensis Harlan (Fossil 

 Dolphin) Miocene, Calvert Cliffs, Md." This makes the identification 

 of the specimens rather difficult. However, I have found no mention 

 of the discovery of vertebrae belonging to Lophocetus (Delpliinus) cal- 

 -vertensis and am inclined to believe that the last is a misplaced label. 



Occurrence. — Calvert (possible Choptank) Formation. Calvert 

 Cliffs. 



Genus DELPHINODON' Leidy. 



" The most characteristic tooth, represented in figures 7 and 8, plate 

 XXX, supposed to be a premolar, is very unlike the corresponding 

 teeth, so far as we are acquainted with them, in the distinct species of 

 Sqiialodon. The crown of this tooth is subtrihedral conical, as broad 



1 This and the following genus, founded on teeth, are regarded by Cope as 

 belonging to the Platanistidae but by Zittel as possibly belonging in the anterior 

 series of some member of the Squalodontidae. The discovery of a more complete 

 dentition, only, can settle this question. Cope's classiflcation seems the most 

 2:)robable. 



