10 



ANOMODONTIA. 



THER0M0K0US BEANCH. 



The forms included in this branch or alliance are arranged in a 

 single order, under which heading the characteristic features are 

 noticed. Baur 1 regards the Dicynodontia (Anomodontia) and 

 Theriodontia (Pelycosauria) as entitled to rank as distinct orders of 

 a subclass Theromora (Theromorpha 2 ). The leading features of the 

 members of this branch are their resemblances on the one hand 

 to the Labyrinthodont Amphibians and on the other to the Mono- 

 treme Mammals. 



Order ANOMODONTIA. 



Body lacertiform, the limbs adapted for walking, the tail com- 

 paratively short, and the head frequently also short. Skull with a 

 fixed quadrate, which articulates with the pterygoid, either one or 

 two temporal arcades, and large nasals ; in the typical forms the 

 pterygoids meeting in front of the basisphenoid, which they also 

 join, but diverging anteriorly (fig. 4); palatines generally small, 

 and placed internally to the pterygoids. When the temporal arcade 

 consists of only a single chain of bones, it is, at least usually, a 

 squamoso-maxillary one. Dentition thecodont, but the teeth fre- 

 quently anchylosed to the jaws. Vertebras amphicoelous and often 

 notochordal ; dorsals with longer or shorter transverse processes ; 

 anterior ribs usually double-headed, with the tubercle articulating 

 with the transverse process of the arch, and the capitulum generally 

 attached to a facet on the anterior border of the centrum. Pectoral 

 girdle usually with a distinct precoracoid, suturally united with 

 the coracoid and the acromial process of the scapula, and entering 

 into the glenoid cavity. Clavicles, a T-shaped interclavicle, and 

 apparently a sternum, present. Humerus (fig. 7) with distinct 

 distal condyles, an entepicondylar (ulnar) foramen, and a more or 

 less expanded delto-pectoral (radial) crest. Pelvis (fig. 3) with the 

 component bones frequently anchylosed into an innominate, the 

 ischium and pubis united by a long suture, in which there may be 

 a small obturator foramen ; body of ilium more or less in advance of 

 acetabulum. Tarsus (when known) with one centrale, and the 



1 Journ. Morphol. vol. i. p. 102 (1887). 



2 This term was withdrawn by its founder Prof. Cope, on account of having 

 been previously applied to the Amphibia Ecauclata. 



