XI NOTHOSAURI PLESIOSAURI 477 



South Africa, probably in Triassic sandstone. Very similar 

 specimens are known from Sao Paolo in Brazil. 



Fam. 2. Nothosauridae. — With sixteen to twenty-one cervical 

 and three to five sacral vertebrae. The vertebrae are biconcave. 

 The clavicles are strong ; the interclavicle is much reduced. 

 Coracoids with distinct acromial processes. 



Nothosaurus mirabilis, of the Muschelkalk of Germany. 

 Total length about ten feet. Length of head about one foot. 

 The teeth are very irregular. About five slender, long teeth 

 are implanted in each side of the premaxilla, with wide spaces 

 between them, similar to those of the symphysial portion of the 

 lower jaw. Those of the maxillaries are numerous and small, 

 except two large pairs in the anterior portion, on a level between 

 the orbits and nostrils. The upper and lower teeth overlap, or 

 cross each other. The palate of the long and slender skull is 

 quite bony, without anterior palatal or infra-orbital vacuities. 



Larioscturus halsami, about one foot in length, from the 

 fresh-water deposits of the Upper Trias in Lombardy. Neck 

 with about twenty, tail with about forty vertebrae. Head com- 

 paratively shorter ; more triangular than in Nothosaurus ; palate 

 with small infra-orbital vacuities. The number of the phalanges of 

 the fingers and toes is apparently 2, 3, 4, 4, 3 and 2, 3, 4, 5, 4. 



Anarosaurus pumilio, of the Muschelkalk, near Magdeburg, 

 and Neusticosaurus and Simosaurus of the same geological age, 

 are allied forms. 



Order II. PLESIOSAURI. 



The limbs are transformed into hyperphalangeal paddles. The 

 clavicles are small, and are overlapped ventrally by the strongly 

 developed acromial processes of the scapulae. The vertebrae are 

 slightly biconcave or plane. The neck consists of at least twenty 

 vertebrae ; those of the thoracic region have long transverse 

 processes ; the sacral vertebrae are mostly reduced to two or 

 one. Very large, massive animals. 



Fam. 1. Pliosauridae. — About twenty cervical vertebrae, with 

 proximally bifurcated ribs. The scapulae do not meet ventrally ; 

 they enclose with the coracoids a single large foramen, and are 

 fused with the clavicles. Pliosaurus, the principal genus, con- 

 tains several species of gigantic size ; for instance, P. grandis, of 

 the Kimmeridge clay. Upper Oolite, of England, has a skull 



