1869. |] HUXLEY—CLASSIFICATION OF DINOSAURIA. 33 
tures far surpassing in size the largest of existing reptiles, will, it 
is presumed, be deemed sufficient ground for establishing a distinct 
tribe, or suborder, of Saurian reptiles, for which I would propose the 
name of Dinosauria. 
“Of this tribe the principal and best-established genera are the 
Megalosaurus, the Hyleosaurus, and the Jguanodon, the gigantic 
crocodile lizards of the dry land, the peculiarities of the osteological 
structure of which distinguish them as clearly from the modern ter- 
restrial and amphibious Sauria as the opposite modifications for an 
aquatic life characterize the extinct Enaliosauria, or marine lizards” *. 
Further on it is stated that ‘‘ the Reptilian type of structure made 
the nearest approach to mammals” in the Dinosauria (1. c. p. 202). 
Every character which is here added to Von Meyer’s diagnosis 
and description of his Pachypoda has failed to stand the test of eri- 
tical investigation ; while it is to birds and not to mammals that 
the Dinosauria approach so closely. ‘There is, in fact, not a single 
specially mammalian feature in their whole organization. 
Even in point of etymological appropriateness, the term “ Dino- 
sauria” is no more fitting for reptiles of which some are small, 
than “‘ Pachypoda” is for reptiles of which some have slender feet ; 
but as Von Meyer’s name has never obtained much currency, it may 
be well to allow justice to give way to expediency, and to retain the 
name of Dinosauria for those reptiles which agree in all the most 
important and characteristic parts of their structure with Megalo- 
saurus and Iquanodon. 
The group thus limited is susceptible of very clear diagnosis from 
all other reptiles, inasmuch as its members present the following 
combination of characters :— 
1. The dorsal vertebrae have amphiccelous or opisthoccelous cen- 
tra. They are provided with capitular and tubercular transverse 
processes, the latter being much the longer. 
2. The number of the vertebree which enter into the sacrum does 
not fall below two, and may be as many as six. 
3. The chevron bones are attached intervertebrally, and their 
rami are united at their vertebral ends by a bar of bone. 
4, The anterior vertebral ribs have distinct capitula and tubercula. 
5. The skull is modelled upon the Lacertilian, not on the Croco- 
dilian type. ‘There is a bony sclerotic ring. 
6. The teeth are not ankylosed to the jaws, and may be lodged in 
distinct sockets. They appear to be present only in the premaxille, 
maxille, and dentary portions of the mandible. 
7. The scapula is vertically elongated ; the coracoid is short, and 
has a rounded and undivided margin. There is no clavicle. 
8. The crest of the ilium is prolonged both in front of and 
behind the acetabulum; and the part which roofs over the latter 
cavity forms a wide arch, the inner wall of the acetabulum having 
been formed by membrane, as in birds. 
9. The ischium and pubis are much elongated. 
10. The femur has a strong inner trochanter ; and there is a crest 
* Prof. Owen’s “ Report on British Fossil Reptiles,” 1841. 
VOL, XXVI.—PART I. D 
