PAREIASAURI 305 



of the vomer, palatines, and pterygoids are recurved and arranged 

 in several longitudinal rows. There is a small incisive foramen 

 in the premaxilla ; the choanae lie within the j)terygoids. The 

 palate has a pair of large lateral vacuities. Between the squa- 

 mosal and quadrate is a small foramen, as in Belodon and 

 Sjohenodon. The nares are terminal, bordered behind by the 

 nasals, and divided by the premaxillaries. The occipital condyle 

 is a single knob, but the lateral occipital bones also partake in 

 its formation. The shoulder-girdle is strong. The scapula 

 slants backwards, is broad, and possesses a longitudinal spine, an 

 almost exclusively Mammalian character. The scapula, coracoid 

 and precoracoid are fused together, and are united ventrally 

 with those of the other side. There is a T-shaped interclavicle, 

 a pair of clavicles, and a pair of slender, long cleithra, which 

 extend along the upper anterior margin of the scapulae. The 

 humerus possesses enormous crests. The broad ilium is 

 attached to two, or perhaps three, sacral ribs. The acetabulum 

 is closed. The pubes and ischia are united into one broad 

 mass of bone, and the obturator-foramina seem to be just large 

 enough to permit of the passage of the nerve. Both fore- and 

 hind-limbs are plantigrade and five-toed. The tibia articulates 

 with one large bone, which is supposed to represent the united 

 astragalus and calcaneum, the latter being without an indication 

 of a prominent heel, although there is a tendency to develop the 

 crurotarsal into the chief joint. The number of vertebrae amounts 

 to eighteen presacrals, eight to ten of which are oervicals. There 

 are two or three sacral and about twenty-four mostly shortened 

 caudal vertebrae. The latter possess intercentral wedges and 

 chevron-bones ; wedges occur also between the cervical and some 

 thoracic vertebrae. Some of the posterior cervical ribs are very 

 peculiar — straight, broadened out, turned backwards, partly over- 

 lapped by one another, and 18 inches long, recalling the first two 

 ribs of the crocodiles. Sternum and abdominal ribs are unknown. 

 Mginia mirabilis. — The skull (Fig. 5 4, A, p. 2 8 ) — nothing else 

 is known — indicates one of the most remarkable reptiles hitherto 

 found on this side of the Atlantic. It was discovered in the 

 Eed Sandstone of Elgin (Lower Trias). The skull reminds us in 

 its general shape and by its spikes and horns of the little American 

 Iguanoid lizard, Phrynosoma. The length of the cranium is 

 about 6 inches, the distance between the tips of the two largest 

 VOL. VIII ^ 



