LIASSIC ICHTHYOSAURS. 85 



relative size and strength of the fore paddles, that it was more littoral in its habits than 

 the majority of these marine Saurians. 



Saltford, near Bath, and the Penarth Beds (Rhcetic) of Glamorganshire are among 

 the localities of Ichthyosaurus latimanus. 



m 



. Ichthyosaurus brachyspondylus, Oto. Tab. XXIX, figs. 3 — 6. 



This species is founded on vertebral characters, the centrums being shorter in 

 proportion to their height and breadth than in any other that has come under my 

 observation. 



In the abdominal centrum, the subject of figures 3 — 5, Tab. XXIX, the breadth of 

 the articular terminal surface (ib., fig. 4) is 2 inches 11 lines; the vertical diameter is 

 3 inches, while the antero-posterior extent does not exceed 11 lines. In a more 

 posterior centrum (ib., fig. 6) in which the diapophysis (d) has descended to contact with 

 the parapophysis, the same proportions are preserved with slight diminution of size. In 

 a larger raid-dorsal centrum of this species which I examined in the private collection of 

 Mr. Rose, of Swaffham, the breadth was 3 inches 8 lines, the height 3 inches 9 lines, 

 but the length did not exceed 1 inch 5 lines. 



In a collection of fossils from Mid-Jurassic beds in the Province of Moscow, sub- 

 mitted to me by Col. Kiprianoff, in 1853, were centrums showing the same dimensional 

 characters, together with a low medial ridge dividing the under surface, which is, like- 

 wise, present in the British specimens. Col. Kiprianoff adopted the name, with my 

 determination, of his Ichthyosaurian specimens, other evidences of which have since 

 been detected and described in a valuable contribution to Russian palaeontology by 

 Prof. Trautschold.i 



D. Conclusion. 



Although a study of the evidences of Ichthyopterygian organisation, of which, and its 

 modifications, as exemplified at the Liassic period, the results are given in the foregoing 

 pages, has left the impression, mainly, of the great additions which wait to reward subse- 

 quent cultivators of this field of comparative osteology, I am unwilling to quit it without 

 giving expression to some of the general notions which its cultivation has suggested. 



Palaeontology has been regarded, if not defined, as including a kind of knowledge of 

 parts, or of structures, in such degree interdependent that, any one being given, others 



1 Trautschold (Prof. H.), ' Erganzung zur Fauna des Eussiscben Jura,' 8vo, 1876, p, 5. 



