34 ICHTHYOPTERrGlA. 



dorsals and anterior caudals narrowed superiorly. In the 

 cervicals and dorsals the cupping of the posterior face is 

 confined to the central region, as in the cervicals of 

 Ojpkihalmosaurus icenicus. The dorsals agree precisely in 

 size with those of the type skeleton, and have the costal 

 tubercles of similarly small size. Owen figured the above 

 mentioned dorsal under the name of /. latimanus (see 

 infra, pp. 53, 54). 



Gunnington Collection. Purchased, 1875. 



47424. A femur, probably belonging either to the present or a 

 closely allied species; from the Oxford Clay of Peter- 

 borough, Northamptonshire. 



Sharp Collection. Purchased, 1876. 



Incertce Sedis. 

 ** Ichthyosaurus (?) thyreospondylus, Phillips l (e^Owen 2 ). 



Syn. (?) Ichthyosaurus brachyspondylus, Owen 3 . 



Of uncertain generic position, and only provisionally admitted as 

 a species. Known only by detached vertebral centra remarkable 

 for their very short antero-posterior diameter. 



I. thyreospondylus of Owen was founded upon vertebras preserved 

 in the Bristol Museum, of which the horizon is not stated ; that 

 form has been quoted as of Liassic age, but Phillips suggests that the 

 types are from the Kimeridge Clay of Weymouth. The vertebras 

 described by Owen under the name of /. brachyspondylus appear 

 very similar to those figured by Phillips, but in this case also no 

 geological horizon is given. Owen, indeed, states that similar 

 vertebras are found in the higher Jurassic of Eussia, but those 

 figured by Kiprijanoff in the ' Mem. Ac. Imp. St. Petersbourg,' 

 vol. xxxi. art. 6, pi. ix., under the name of Polyjjtychodon, but 

 subsequently referred to 2". brachyspondylus, are of Cretaceous age. 



Hab. Europe (England). 



46794 a. The centrum of a cervical vertebra ; from the Kimeridge 

 Clay, near Devizes, Wiltshire. 



Gunnington Collection. Purchased, 1875. 



46794 C. The centrum of a smaller cervical vertebra ; from the 

 same locality. Gunnington Collection. 



1 Geology of Oxford, pp. 307, 337 (1871). 



2 Eep. Brit. Assoc, for 1839, p. 124 (1840). 



3 Liassic Eeptilia (Mon. Pal. Soc), pt. iii. p. 127 (1881). 



