ORDER SAUROPTERYGIA. 



IO77 



original character as long bones, and are separated by a well-marked 

 interval. 



Another exclusively Liassic and perhaps Rhaetic genus is Eret- 

 mosaurus, which had a long neck and probably a small head like 

 Pksiosaurus, but with a very different type of pectoral girdle. Thus 

 the coracoids had no median production in advance of the glenoid 

 cavity ; while the scapulae were large, and articulated together in the 

 median line, and posteriorly were united by their whole length with 

 the coracoids, leaving only very minute coracoidal foramina. If an 

 interclavicle were present it had 

 become fused with the scapulae. 

 The type species is from the 

 Lower Lias, but there is another 

 in the Upper Lias. The largest 

 genus of the family is, however, 

 Cimoliosaurus, in which we may 

 conveniently include those forms 

 described under the names of 

 Discosaurus, E/asmosaurus, Mau- 

 isaurus, Polycotylus, Murcenosau- 

 rus, and Colymbosaurus. This 

 genus was originally described 

 upon the evidence of a very 

 large species from the Cretaceous 

 of New Jersey, with which Dis- 

 cosaurus, and probably Elasmo- 

 saurus, are specifically identical. 

 The New Zealand Cretaceous 

 species described as Mauisaiwus 

 is closely allied ; and it has yet 

 to be proved that the type species 

 is even specifically distinct from 

 the European C. constridus. Many of the other species differ con- 

 siderably from these typical forms, but if generic divisions are once 

 made it seems impossible to know when to stop. 



The genus in the above extended series may be characterised as 

 follows. The teeth and skull are relatively small, the mandibular 

 symphysis is short, and the neck usually very long, with the anterior 

 vertebrae relatively small. The vertebrae are more or less elongated, 

 and generally have the neural arches and the cervical ribs completely 

 anchylosed to the centra in the adult ; the costal articulations always 

 forming single facets in the cervical region. In the pectoral girdle 

 (fig. 988) the scapulae have very large and wide ventral plates, meeting 

 in the middle line, without any trace of an interclavicle, and usually 

 sending down a median process to join the coracoids, and thus com- 



- Ventral aspect of the right 

 humerus, radius (T), ulna (z), and pisiform 

 (F) of Cimoliosaurus trochanterius ; from the 

 Kimerids;e Clay of Dorsetshire. Reduced. 

 (After Hulke.) 



