760 J. W. HULKE ON ORNITHOPSIS, 
description implies it does in Camarasaurus*. In this latter, also, 
the upper surface of the cervical parapophysis exhibits a very cha- 
racteristic excavation, which is wanting in the known cervicals of 
Ornithopsis. These, however, might be regarded as trivial differ- 
ences, not entitled to generic rank. 
In the neural arch and processes a similar interchange of concor- 
dances and differences is observable. In Ornithopsis and Camara- 
saurus, as also in Epanteriast, the free end of the neural spine is 
expanded transversely in some of the trunk-vertebree ; but its con- 
struction is less complex in Camarasaurus, in which, too, the deep 
entering angle between its postzygapophysial roots for the attachment 
of the interspinous ligament, so noticeable in Ornithopsis, is absent. 
- A more notable difference, to which my attention has been called 
by Prof. Copez, is the bifid divergent form of the neural spine in a 
dorsal. vertebra of Camarasaurus, which, by the situation of its 
parapophysis, held a correspondent place in the vertebral column to 
that of my first vertebra (No. 144, coll. H.). Although the free ex- 
tremity of the spinous process is defective, enough is preserved to 
show that it could not have had the remarkably forked divergent 
form represented in Prof. Cope’s figure 2. 
I agree with Prof. Cope that this is a difference certainly of 
generic value. 
The presence of a supplemental articulation, comparable in prin- 
ciple to zygosphene and zygantrum, in both Ornithopsis and Camara- 
saurus, is another singular agreement in which Amphicelas also 
participates, as it does in the lateral foramen and internal chambers§. 
In both these North-American Dinosaurs the zygosphene has the 
form of an inverted wedge, and its base is represented free and un- 
attached, resembling in form and connexion the zygosphene repre- 
sented by Phillips in Megalosaurus and in Ceteosaurus oxoniensis, 
Phillips ||: but in the corresponding vertebra of Ornithopsis the 
zygosphene is a laterally compressed vertical plate, the posterior 
face of which is an oblong, from each of the lower angles of which 
the stout border of a thin sheet slants downwards and forwards 
upon the posterior margin of the corresponding neurapophysis, 
near the union of this with the centrum. The two sheets of opposite 
sides in this way form a sloping eave, which in the articulated ver- 
tebral column (when the zygosphene is received into the interpre- 
zygapophysial notch), roofs in that part of the spinal canal, which, 
owing to the relative shortness of the neurapophysis, would be 
otherwise comparatively unprotected. This also appears to me a 
difference of more than trivial value. 
Full and complete descriptions of the vertebrae of Morosaurus, 
Apatosaurus, and Allosaurus are still wanting: their discovery is 
* Pal. Bulletin, No. 28, p. 284. 
t+ Epanterias, not having chambered externally opening dorsal centra, needs 
no ites notice here. 
¢ Cope, Pal. Bulletin, No. 28; Proc. Am. Phil. Soe. pl. 1. fig. 2. 
g The centra of Amphicolias ‘being amphiccelian or platyccelian, this alone 
suffices to separate it from Ornithopsis and Camarasaurus, 
| ‘Lhe Geology of Oxford,’ p. 256, diagram 87. 
