30 ICHTHYOPTERTGIA. 



42282. The centrum of a large middle dorsal vertebra : from the 

 {Fig.) Kimeridge Clay (Upper Jurassic) of the Isle of Portland. 

 The vertical diameter of this specimen (fig. 15) is 0,125, 

 the transverse 0,110, and the length 0,048. In one of 

 - the type posterior dorsals described by Phillips the corre- 

 sponding diameters are 0,078, 0,073, and 0,032. 



Purchased, 1869. 



44637. The centrum of a caudal vertebra probably referable to this 

 species ; from the Kimeridge Clay of Weymouth, Dorset- 

 shire. The specimen is slightly distorted. Its vertical 

 diameter is 0,061, and the transverse 0.051. 



Purchased, 1873. 



Ichthyosaurus (?) dilatatus, Phillips 1 . 



Centra of dorsal and caudal vertebrae described as of the general 

 type of those of /. trig onus, but relatively wider and shorter, and 

 rather less deeply cupped. In the undermentioned specimens the 

 crowns of the teeth are very long and deeply fluted. 



In the absence of figures of the types it is difficult to refer 

 other specimens with certainty to this species, which appears to have 

 attained large dimensions, and the following references are there- 

 fore provisional. The first of the undermentioned specimens 

 agree so closely with I. hildesiensis, Koken 2 , from the Lower Green- 

 sand of North Germany, that were it not for their much lower 

 geological horizon they might be referred to the same species. If 

 the absence of large teeth be an invariable characteristic of Ojphthal- 

 mosaurus the following specimens are not referable to that genus. 



Hah. Europe (England). 



45984-7. A series of associated bones ; from the Kimeridge Clay 

 (Upper Jurassic) of Swindon, Wiltshire. These speci- 

 mens comprise the basioccipital, basisphenoid, fragments 

 of jaws with teeth, and eight centra of anterior and 

 middle dorsal vertebrae. The vertebrae agree approximately 

 in size with No. 2-1684 b of I. trigonus, but are shorter 

 and wider, with the cupping of the faces rather less deep. 

 In one example the vertical diameter is 0,076, the trans- 

 verse 0,087, and the length 0,034. Although the distor- 

 tion to which they have been subject renders exact com- 

 parison difficult, they appear to be wider than the dorsals 



1 Geology of Oxford, p. 307 (1871). 



2 Zeitschr. deutsch. geol. Ges. vol. xxxv. p. 761 (1883). 



