ANOMODONTIA. 



11 



phalangeals of the manus and pes 2, 3, 3, 3, 3 in number ; and the 

 structure of the foot approximating to a Mammalian type. 



In the Dicynodontia and the typical Theriodontia the skull has 

 both parieto-squamosal (post-temporal) and postorbital bars ; but 

 the former unites with the supraoccipital so as to leave no post- 

 temporal fossa (fig. 6), and all the bones of the occiput tend to 

 anchylose together into a large plate (fig. 5) ; this arrangement pro- 

 ducing a remarkably Mammalian type of occiput \ Secondary 

 posterior nares may be formed in the above-mentioned suborders by 

 the development of palatal plates to floor the nasal passage. 



The precoracoid appears to correspond with the bone in the 

 pectoral girdle of Monotremes usually termed the epicoracoid. The 

 acromial process of the scapula is strictly comparable with that of 

 Monotremes, although in the latter it articulates only with the 

 clavicle. The coracoid and precoracoid are relatively small in com- 

 parison with the scapula. 



As a rule, abdominal ribs appear to have been absent 2 , while 

 there seem to be no traces of a dermal armour in most forms. 

 Sclerotic plates may be developed in the orbit. In the cervical 

 region it appears that, as a general rule, the ribs articulate to one 

 process on the centrum, and to another on the arch, as in Crocodiles. 

 In most of the dorsal vertebrae the capitular articulation usually 

 forms a distinct facet on the anterior border of the centrum 3 , but 

 in some American forms there is no distinct facet, and occasionally 

 all the ribs seem to have had single heads ; in Embolopliorus the 

 capitular articulation is placed on the intercentrum, from which it 

 appears to have been transferred to the anterior border of the 

 centrum in other forms by the diminished size and final loss of the 

 intercentrum. 



1 It may be observed that in the occiput of the Dicynodonts (figs. 5, 6) Owen 

 considered that the exoccipital met above the foramen magnum, as in Crocodiles, 

 and that the bone marked ip in fig. 6 represented the supraoccipital. Huxley 

 (' Quart. Journ. Geol. Soc.' vol. xv. pp. 652-653) pointed out that the supra- 

 occipital is represented in the upper part of the compound occipital plate, 

 forming the upper border of the foramen. The three bones marked ip and 

 pa in fig. 6 were regarded by Huxley as the parietals ; but the distinctness of 

 the median element was indicated by Seeley in the ' Phil. Trans.' for 1889, 

 pp. 230-235, where it is identified with the interparietal. The same writer 

 would regard the bones here termed parietals as consisting of three elements, 

 the part marked pa in fig. 6 being regarded as probably an epiotic. The 

 correctness of Huxley's interpretation of the supraoccipital is shown by C 'iste- 

 cephalus (fig. 12), where the supraoccipital, exoccipitals, and basioccipital remain 

 separate. 



2 Present in Theroplcura, Cope. 



3 Cope, Proc. Amer. Assoc, vol. xxxiii. p. 475 (1885) remarks on the approxi- 

 mation to a Mammalian type presented by this mode of articulation. 



