ZOOLOGY. 2138 
the proétics and opisthoties from its support constitutes a step 
towards the liberation of the quadratum, and places it nearest the 
Lacertilia, in the order. This indication is confirmed by the sim- 
ple premaxillary bone, and the lack of quadratojugal arch. 
Among Lacertilia, the Chamzleontide make the nearest ap- 
proach, though a remote one. This is seen in the posterior pro- 
longation of the dentary bone, and the often rudimental dentition. 
The nearest approach outside the Archosauria is to the Rhyn- 
chocephalia, as represented by the existing genus, Sphenodon* 
Here the canine teeth begin to show an increased development, 
and the other teeth to become obsolete or confluent. The nearest 
approach to the great development of the squamosal in Anomo- 
dontia is seen in this genus, and they both possess an ossified sep- 
tum orbitorum. In both, the posterior extremity of the pterygoid 
is much expanded, and supports a columella. 
In summing up, the following significance may be attached to 
the above characters. From this it will be seen that the Anomo- 
dontia present a remarkable combination, and well deserve the 
appellation of a “generalized type.” Characters of Crocodilia 
are: 1. Presphenoid keel; 2. Expanse of pterygoid to unite with 
it; 3. Foramen of the mandible; 4. Reduction of, zygomatic bone. 
Testudinata: 1. Edentulous: jaws; 2. Codssified mandibular rami, 
with foramen. Rhynchocephalia: 1. Largely developed squamo- 
sal; 2. Osseous interorbital septum; 3. Distinct ? epiotic; 4. Bi- 
concave vertebre; 5. Columella; 6. Foramen parietale;— the 
last two belonging ‘also to the Lacertilia, which have further in 
common with Lystrosaurus: 1. Absence of quadratojugal arch ; 
2. Simple premaxillary bone (mostly). 
Ichthyopterygia: 1. Parietal and quadrate branches of squamo- 
sal; 2. Sessile suspensorium of quadrate; 3. Posterior flat opis- 
thotic. 
Dinosauria: 1. Elongate sacrum; 2. Ribs continued to sacrum ; 
3. Capitular and tubercular attachment for ribs on neural arch and 
centrum, respectively. 
From the preceding evidence, it is clear that the Anomodontia 
constitute the most generalized order of Reptilia of which we have 
any knowledge; and occupying, as it does, almost the first or oldest 
place in geologic time among the Reptilia, —7. ¢., in the Triassic 
period, —it justifies the statement that the peculiarly older 
* See Giinther, Trans. Royal Society, 1867, Pt. I, p. 1. 
