ORDER SAUROPTERYGIA. 



1079 



and 40 feet, and having nearly 40 cervical vertebrae. In the second 

 group, which apparently corresponds to the genus Polycotylns of Pro- 

 fessor Cope, we have, in the Oxford Clay, C. oxoniensis and C. eury?nerus, 

 in which the humerus articulates with only the radius and ulna, and in 



Fig. 1000 bis.— A. cervical vertebra of Cimoliosanrus plicatus ; from the Oxford Clay. One- 

 fifth natural size. 1, Posterior; 2, Inferior; 3, Anterior aspect. (After Phillips.) 



the Kimeridge the larger C. trochanter ins, in which the pisiform also joins 

 the humerus (fig. 998). The very small C. valdenszs, of the Wealden, may 

 have been of freshwater habits ; while in the Chalk we find the larger C. 

 Bernhardt. This group appears to have been also represented in the 

 Cretaceous of North America and New Zealand. A species from the 

 Cretaceous of Kansas, described under the name 

 of Trinacro?neron, has three bones articulating 

 with the humerus. 



The imperfectly known genus Polyptychodon 

 (Lutkesaurus), of the Middle and Upper Cre- 

 taceous of Europe, appears to be allied to 

 Cimoliosanrus, but with a relatively larger 

 head and teeth, and probably with a much 

 shorter neck. The teeth, which are very 

 abundant in the Cambridge Greensand, have 

 subcorneal crowns, with strongly - marked 

 ridges, of which a considerable number gene- 

 rally stop short of the summit. These Rep- 

 tiles must have attained huge dimensions. 

 The genera we have now to consider indicate 

 a different branch from that to which the two 

 preceding genera belong. The first of these 

 is Thaumatosaurus (in which Rhomaleosaw'tis 

 may be included), typically occurring in the 

 Great Oolite of Wiirtemberg, but extending 

 downwards to the Lower Lias and upwards 

 to the Kimeridge Clay of England. In these 



forms the skull and teeth were relatively large, the latter being 

 often carinated, and the mandibular symphysis (fig. 996, b) com- 

 paratively short, with the first five or six teeth enlarged. The neck 



VOL. II. N 



Fig. 1001. — Dorsal as- 

 pect of part of the left pelvic 

 limb of Peloneustes phil- 

 archus; from the Oxford 

 Clay. One -sixth natural 

 size, fe, Distal half of 

 femur ; t, Tibia ; f, Fibula; 

 t' , Tibiale ; z", Intermedium ; 

 /', Fibulare. The tibia is 

 drawn rather too small in 

 proportion to the fibula. 



