CHIPvOCEXTRID^. 
93 
1875. Portheuii molossus, E. D. Cope, Vert. Cret. Form. West (E,ep, 
U.S. Geol. Surv. Teriit. vol. ii.), pp. 184, 194, fig. 8 (woodc.),. 
pis. xxxix.-xli.; pi. xliv. figs. 5, 10, 11; pi. xlv. figs. 9-11. 
1892. Portheus mulossus, A. E. Crook, Palaeontogr. voL xxxix. p. 114, 
pi. xviii. 
1898. Xiphactmus audax, A. Stewart, Kansas Unix. Quart. [A] vol. viir 
p. 119, pis. xii.-x. ^ -/y 
Type. Skull, with vertebrae and fin-rays^' 9u^. 9^-^, 
The type species, of large size, the cranium attaining a length of 
0-35. Premaxilla with two teeth, the foremost usually having- 
two thirds the diameter of the second. Maxilla three times as long 
as the premaxilla, much deepened at the anterior palatine articu^ 
lation, and its oral border nearly straight; about five enlarged 
teeth in its anterior half. Depth of dentary at the symphysis 
nearly equalling one third the total length of the mandibular ramus,- 
and its oral border very slightly undulating ; about five enlarged 
teeth in front, the two foremost separated by a transverse groove 
from the three behind. Dental crowns smooth and not facetted, 
not curved at the apex. Cheek-plates marked with very feeble 
large tubercles and rugae. 
Form. (^' Log. Upper Cretaceous (Aiobrara Group): Smoky Hill, 
Kansas, U.S.A. 
P. 6326. Slab of friable chalk exhibiting a nearly complete head, 
right lateral aspect, associated with numerous vertebral 
centra, remains of the pectoral and pelvic arches, some of 
the pectoral fin-rays, and the greater part of the pelvic 
fins. The two halves of the pelvic arch are shown to be 
firmly united by suture, and one of the pelvic fins seems 
to be better preserved than any hitherto described. It 
exhibits five broad rays, all very finely subdivided and 
articulated in step-like sutures at their expanded distal 
end. The foremost ray is much the largest; the three 
diminishing hinder rays are crushed so as to exhibit their 
loosely apposed right and left halves. Purchased, 1891.. 
P. 6327. Series of caudal vertebrae. Purchased, 1891. 
The following specimens from the English Chalk indicate a form 
of Portheus as large as P. molossus, probably distinct, but not 
specifically determinable :— 
25923 X. Portion of cranium ; Chalk, Sussex. Dixon Coll. 
4057. Pemains probably of maxilla and premaxilla ; Chalk, Lewes. 
Mantell Coll, 
