ENCHODONTID35. 
189 
(Proc. Amor. Phil. Soc. vol. xii. 1872, p. 349) belong to a member 
of the family Dercetidse. The following species are distinguished, 
but are not represented in the Collection : — 
Stratodus apicalis, E. D. Cope, Joe. cit. 1872, p. 349, and Vert- 
Cret. Form. West (Rep. U.S. Geol. Surv. Territ. vol. ii. 
1875), p. 227, pi. xlix. tigs. 6-8. — Upper Cretaceous 
(Niobrara Group); Smoky Hill River, Kansas. [Jaw 
with teeth ; Cope Collection.] 
Stratodus oxypogon, E. D. Cope, Proc. Amer. Phil. Soc. vol. xvii. 
(1878), p. 180. — Upper Cretaceous ; Kansas. [Remains 
of jaws ; Cope Collection.] 
Family ENCHODONTIDiE. 
Supraoccipital bone not prominent, but extending forwards to 
the frontals and separating the small parietals in the median line ; 
squamosal reduced, only partly covering the otic region, which 
projects laterally ; no basicranial canal ; snout not produced ; cheek - 
plates well developed. Mandibular suspensorium vertical or 
1 ncli ned backwards, and gape of mouth wide ; premaxilla delicate, 
considerably extended and excluding a great part of the slender 
maxilla from the uppor border of the mouth ; teeth fused with the 
supporting bone, not in complete sockets, those on the pterygo- 
palatine arcade and dentary the largest. Opercular apparatus 
complete, with few slender branchiostegal rays and no gular plate. 
Vertebral contra well ossified, none with transverse processes ; ribs 
not completely encircling the abdominal cavity ; a compound 
b} pural bone at the base of the tail. Intermuscular bones present. 
I'in-fu] era absent; the rayed dorsal fin never much extended, 
usually near the middle of the back, and sometimes an adipose fin 
behind. Scales delicate or absent ; but occasional longitudinal 
8e ries of scutes, the dorsal series, when present, being unpaired. 
The nearest living allies of this extinct family appear to be the 
Odontostomidsa and Alepisaurid®, in both of which the margin of 
tbo upper jaw is formed exclusively by the premaxilla, while in the 
first the large teeth are depressible. Only three genera are known, 
{j donfostomus, Omosudis, and Alepisaurus ( Plagyodus ), all from the 
deep sea. 
Synopsis of Genera. 
T One large terminal palatine tooth. 
Dorsal fin in front of anal ; no postelavicular 
plate 
Enchodus (p. 190). 
