‘ 
1872. ] 333 [Cope. 
The third form of spine is represented in most of the species, but 
one series of rays with spine may not be referable to any of them. The 
latter is flat and curved, the convex edge trenchant beyond the middle. 
The posterior edge is obtuse but narrow, and exhibits a slight groove on 
one side medially ; proximally there is a shallow rabbet whose floor is 
transversely rugose. Several layers of the tissue of the spine beyond the 
basal portion are delicately longitudinally striate. The distal half is 
broken away ; length of fragment, one foot ; width, 1.5 inches ; thickness 
at middle, 5 lines. 
The species of this genus may be distinguished as follows : 
a, Teeth without acute edges. 
Large maxillaries five ; second premaxillary larger than the first ; third 
mandibular large, behind a cross-groove ; last large mandibular followed 
by 16,—8 small teeth....... fey Se ees y ia wetes Ve Cet wa Lo MOLOBBUS. 
Large maxillaries, three ; first piemaxillary larger than second ; third 
mandibular small, no cross-groove in front of it ; twenty small teeth be- 
hind last large mandibular....... Ev HA Oe es Thoms: 
ad, Large teeth with cutting angle in front. 
Teeth large, not compressed............ eG cdeawes. yb ONGUUaiis. 
PoRTHEUS MOLOSSUS. Cope. 
(Proc. Amer. Philos. Soc., 1871, p. 178.) 
Represented by four individuals, one from Fox Cafion, near Fort Wal- 
lace, with complete cranium, and many vertebre and radii ; a second from 
another part of the same ravine with large part of cranium, and a third 
and fourth from lower Butte Creek bluffs, both with fragments of cranium 
and other portions. In the first specimen the jaws are perfect and denti- 
tion complete. 
The premavillary is vertically oval, convex externally, nearly flat within, 
and more than half underlaid by an anterior lamina of the maxillary, 
The anterior or median margin is regularly convex and exhibits no sur- 
face or suture for union with the bone of the opposite side. Its posterior - 
margin extends obliquely backwards to beneath the superior articular 
condyle of the maxillary and has a ragged margin, though the suture is 
squamosal. Its superior margin is deeply inflected in front of the con- 
dyle and then convex and thickened. The anterior margin is thick and 
rugose with tubercular exostoses. There are but two teeth, which are 
very large, and directed obliquely forward; the first is two-thirds the 
diameter of the second. 
The mavillary is a large laminiform bone, with the upper margin con- 
siderably thickened proximally but much thinned distally. It is abruptly 
contracted at the distal two-thirds its length, apparently for the attach- 
ment of a supernumerary bone. The.extremity is curved sabre-shape 
upwards, and has an acute toothless edge. The teeth are, four small, five 
large, and eighteen small. These teeth, except the largest, have cylindric 
‘bases ; the crowns (and bases of the latter) are slightly compressed or 
