THERIODONTIA 307 



The atlas is fused with the axis ; most of the thoracic ribs 

 articulate partly upon the intercentra. The lumbar ribs are 

 very peculiar ; they are much expanded horizontally, and overlap 

 each other, forming thereby intercostal foramina. The broad 

 ilium is attached to three or four sacral ribs. The acetabulum 

 is closed. The ventral side of the pelvis shows a broad 

 symphysis and has a pair of obturator-foramina. The scapula 

 is large, directed backwards, and shows a distinct, very Mam- 

 malian spine ; it is fused with the coracoid and precoracoid. 



The occipital condyle of C. platyceps is kidney-shaped, with 

 the concavity directed upwards ; in C. herryi it is separated into 

 two distinct knobs, the middle, basioccipital portion being 

 apparently wanting. The mandible possesses a long coronoid 

 process which ascends obliquely into the temporal fossa. 



Aelurosaurus, Lycosaurus, Galesaurus, and many others, 

 likewise of the Karroo formation. In the first genus the 

 splenial bones help to form the symphysis of the lower jaw ; teeth 

 are also found on the palate, in opposition to Lycosaurus. This 

 has a skull 6 inches in length ; the dental formula on either side 

 is i. -|, c. -^, m. |- ; the molars are slender, conical, and recurved. 

 Galesaurus seems to have been rather small, the low, triangular 

 skull measuring only 2 to 3 inches in length, with four or five 

 sharply pointed incisors, prominent canines and four or five small 

 multicuspid or deeply serrated little molars. 



Enclothiodon, with several species from the Karroo formation, 

 is of uncertain systematic position, only imperfect skulls being 

 known. The animals must have been large and bulky, the 

 skulls being very massive and at least one foot in length. The 

 premaxillaries and the maxillaries are toothless, their alveolar 

 borders forming cutting, prominent edges. The same applies to 

 the very strong lower jaw; but there is a pair of tooth-like 

 stout projections in the upper and lower jaws in the place of 

 canine teeth. True, enamelled, small, apparently conical or low 

 and perhaps blunt .teeth occur on either side ' in one or three 

 longitudinal series upon the palate, and in corresponding positions 

 on the inner sides of the two halves of the lower jaw. It is 

 doubtful if the upper teeth are carried by the palatines or by the 

 broadened inner flanges of the maxillaries. The choanae seem to 

 lie between the pterygoids and the palatines, incompletely roofed 

 in by ventral extensions of the latter towards the middle line. 



