292 
PROFESSOR H. G. SEELEY OR THE STRUCTURE, ORGANIZATION, 
to note that, in the Mammalian jaw, the foramen by which the cartilage leaves it is 
some distance in advance of the region in which the articulation is placed. This 
condition has always seemed to me conclusive against the articular element persisting 
in the Mammalian jaw. Secondly, the dentary bone attains a varying development. 
In Galesaurus it is very large, and apparently rises into a coronoid process as well 
developed as in any Mammal. But it seems inconceivable that it could ever come to 
form the articulation with the squamosal if that articulation M^as previously established 
with the sur-angular bone. There appears, therefore, to be a necessity for the preser¬ 
vation of parts which correspond to the dentary and sur-angular and angular elements. 
But I see no such necessity for the preservation of the splenlal bone, which in Crocodiles 
is little more than a long scale on the inner side of the dentary, or of the coronoid 
bone which is internal in position to the coronoid process ; so that I suppose the 
three successive bones on the inner side of the Reptilian lower jaws to become lost in 
the Mammal, and the three external bones to become united and preserved as one 
continuous ossification. It may be within the limits of possibility that, after* the 
articular bone was lost, the angular bone on which it rests also disappeared from the 
changed mechanical conditions which affected its ossification, and that the dentary 
bone, extending backward at its expense, may have eventually invested the outlet 
for Meckel's cartilao’e before its union with the sur-angular bone was obliterated. 
Therefore there are facts which seem to point to a loss of some elements from the 
Reptilian jaw by absence of ossification, and other facts which render the union of the 
remaining bones by a loss of segmentation highly probable. 
Ckc^sification. 
It would be premature at present to do more than recognize the larger groups into 
which the Anomodontia may be divided. Among such sub-ordinal divisions are the 
folio winof 
]?asi-occipital articulation . 
No temporal vacuities . 
No median bar to inter-clavicle 
IMedian bar to inter-clavicle . 
No temporal vacuities . 
Teeth on pterygoid and vomer 
Tripartite occipital condyle 
Descending- process of squamosal 
Not more than one tooth in each maxillai-y 
Large, laterally compressed incisors, sepan 
canines from small pointed molars . . 
[Ex-occipital condyles,] No descending process to’ 
squamosal vpliich articulates with lower jaw. Molar- 
teeth rvitlr poiirted cusps. 
Ex-occipital corrdyles. Molar teeth transversely developed, 
with cusps. 
Ex-occipital condyles. Crirshing teeth orr vornei-, ptery¬ 
goid, arrd rrraxillary. 
ated by 
Sub-order. 
Example. 
Pareiasauku . . 
Fareiasaurus. 
Pkocolophonia . . 
Frocolophoii- 
r Dicynodoxtia . . . 
i 
Dicynodon. 
1 
Genxetotheria . . 
Lycosaurus. 
,^Pely'cosaukia (?) 
Clepsydrops. 
Theriodontia . . . 
Oalesaurus. 
Coty'losauria . . 
Empedias. 
Placodoxtia . 
Flacodus. 
