1891.] Remarks on Reptiles Called Dinosauria. 437 
developed than in the Crocodilia, and sometimes absent. The 
centra of the posterior dorsal vertebræ are flat or slightly con- 
cave at each end, and they have crocodilian transverse processes 
and ribs. The centra of the anterior dorsal and of the cervical 
vertebræ are sometimes concave behind and convex in front 
(opisthoccelous). There are four or more vertebræ in the sacrum. 
The pelvis and bones of the hind limb are in many respects 
very like those of birds. No clavicles have been observed, and 
the fore limb is sometimes very small in proportion to the hind 
limb.” 
One year later Prof: Cope (11) gave the following characters : 
“Limbs ambulatory or prehensile. Ilium horizontal, support- 
ing a long sacrum of five or six vertebre, the anterior derived 
from the lumbar series. The acetabulum thrown forwards, and 
not complete, but perforate. Ischium long, longitudinal, posterior, 
_ Supporting the parts, in front of a process. Ribs free, double- 
headed. Neural arches united’ by suture; chevron bones 
present.” 
The next paper is Prof Huxley’s (12) well-known memoir on 
the classification of the Dinosauria. The order Ornithoscelida 
is created, with two suborders: 
“I. Dinosauria, with the cervical vertebrz irii short, and 
the femur as long as or longer than the tibia. 
II. The Compsognatha, with the cervical vertebræ relatively . 
long, and the femur shorter than the tibia.” 
The Dinosaurs are now characterized fully : | 
“1. The dorsal vertebrae have amphiccelous or opisthoccelous 
centra They are provided with capitular and tubercular trans- 
verse processes, the latter being much the longer. 
2. The number of the vertebre which enter into the sacrum 
does not fall below two, and may be as many as 
3. The chevron bones are attached Se ee and their 
rami are united at their vertebral ends by a bar of bone. 
4. The anterior vertebral ribs have distant capitula and 
tubercula. 
5. The skull is modeled upon the lacertilian, not on the cro- 
Codilian, type. There is a bony sclerotic ring. 
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