41 



ICHTHYODECTES PROG^N^ATHUS, Cope, loc. cit., 1873, 341 ; Scturocephalus 

 ^rognathus, Proceed. Amer. Philos. Soc, 1870, JSTovember. 



Mobrara Cretaceous of the Smoky Hill. 



ICHTHYODECTES MULTIDENTATUS, Cope, loc. cit, 1872, 342. 



Mobrara Cretaceous of the Smoky Hill. 



ICHTHYODECTES'[PEEjSfICIOSUS, Sp. nov. 



Compouud pectoral spines of -this genus, which have heretofore come 

 under my observation in considerable abuudance, exhibit an undulating- 

 cutting margin with low waves, and a nearly uniform thickness. These 

 I have attributed to such species as I. anaides, I. ctenodon^ and I. Jiama- 

 tus. A spine pertaining to a fish of equal or greater size than these 

 has been several times obtained, which evidently belongs to another 

 and more formidably-armed species. 



The cutting edge is coarsely serrate, each x)rojecting tooth marking 

 the end of one of the oblique component rods. The apex of each tooth 

 is the end of a transverse thickening or low ridge of the surface of the 

 spine, so that the cutting edge is equally acute at the bottoms of the 

 concavities as at the rather obtuse apices of the teeth. The cement or 

 enamel layer extends on both sides of the spine 0.75 inch from the cutting 

 edge; it is composed of small aggregated tubercles. Length of frag- 

 ment supporting twenty teeth, 0°^.235; thickness of fragment at mid- 

 dle, 0™.008. Discovered by Professor Mudge. 



DAPTINUS, Cope. 



Proceedings Academy Philadelphia, 1873, 339. 



Daptinus phlebotomus. Cope ; Saurocephalus phlehotomus, Cope, Pro- 

 ceed. Amer. Philos. Soc, 1870, JSTovember ; Hay den's Annual Rept. XJ. S- 

 Geol. Surv., 1871, 416. 



Kiobrara epoch, Rooks and Phillips Counties, Kansas. 

 SAUROCEPHALtrS, Harlan. 



Saueocephalus lanciformis, Harlan, Journal Academy Natural 

 Sciences, I vol. iii, 331; Leidy, Trausac. Amer. Philosophical Soc, 

 1860. 



Cretaceous on the Missouri River. 



Saurocephalus arapahovius, Cope, Proceed. Amer. Philos. Soc, 

 1872, 343. 

 Niobrara epoch of the Smoky Hill, Kansas. 



ERISICHTHE, Cope 

 Proceedings Academy Philadelphia, 1872, 280. 



In this genus the teeth are implanted in deep sockets as in other Sau- 

 rodontidw, and the subalveolar line of foramina seen in Saurocephalus is 

 wanting. The crowns of the teeth are compressed and knife-like as in 

 Daptinus, but those of the anterior parts of the dentary and maxillary 

 bones are greatly enlarged. Maxillary bone short and rapidly tapering 

 to a narrow edentulous extremity. Greater part of the dentary with a 

 rugose band on the inner side of the teeth; its distal portion with a row 

 of small compressed teeth separating the large teeth into two areas. 



