1888.] ANATOMY OF THE MKSOSUCHIA. 431 



as prsepubis. Further, Prof. H. G. Seeley homologizes this prae- 

 pubis with a bone haviiio; similar relations to the other elements 

 of the pelvic girdle thought to be present in OrnWiosauria. But 

 C. K. Hoffmann has abandoned his earlier interpretation of the bone, 

 and he, in a more recent publication, says that he now considers 

 as pubis the bone which once he regarded as prcepuhis (36). Prof. 

 H. G. Seeley finds that the bone commonly accepted as the Croco- 

 dilian pubis is much more slender, and it is much less expanded at 

 the anterior end in all the species from the Lias and Lower Oolite 

 rocks ; and he refers to " some undesciibed types in the collection 

 of A. Leeds, Esq., in which it is reduced to a mere bony style 

 without expansion at either end, comparable in form and substance 

 to a lucifer match" (37). 



It is manifest that the bone here described by Prof. H. G. Seeley 

 in the above quotation cannot be identified with that bone which, 

 from its constant association with the other pelvic bones, and from 

 its close resemblance to the Eusuchian pubis, I have described and 

 figured as the os pubis of these Peterborough Mesosuchians. Al- 

 though I have some knowledge of Mr. Leeds's collection, I have not 

 seen in it such pubic {prcehuhic, S.) bones with undilated ends ; and 

 Mr. Leeds assures me that he has not any such as those to which 

 Prof. Seeley refers. The only bones in the collection at all corre- 

 sponding to Prof. Seeley's description, I have ventured to interpret 

 as the detached styliform atlantal riblets. R. Owen, referring to a 

 Liassic Teleosaur preserved in the Whitby Museum, writes, "Both 

 ischium and pubis are relatively more expanded than in the Gavial " 

 (38). 



In the Liassic Crocodilians, so far as these are known to me, the 

 ossa pubis are similar in form, they have similar connections, and 

 they are essentially identical with the ossa pubis of the Eusuchia. 

 As regards the pelvic element in Ornithosauria, by some authors 

 termed prapubis, with which Prof. H. G. Seeley (in this matter 

 following Quenstedt) homologizes this Crocodilian bone, I have for 

 some time had doubts of its existence as a separate, distinct element. 

 In illustration of the view he adopts concerning it. Prof. Seeley 

 reproduces Quenstedt's representation of the bones in question, as 

 displayed in Quenstedt's \)\a.iQ oi Ptercdactylus {Cycnorhamphus) sue- 

 vicus (39). But these parts are, I suggest, susceptible of another 

 reading ; the paddle- or fan-like bone as H. v. Meyer described it, 

 with narrow short shaft and expanded opposite end, is not, I submit, 

 a bone complete in itself, but merely the ventral symphysial portion 

 of an OS pubis constructed and associated with the other pelvic ele- 

 ments after the common Lacertilian plan. Quenstedt's figure repre- 

 sents the two paddle-like pieces detached from their connections, 

 flatly extended, as he conceived their natural position beneath the 

 abdomen, in advance of the acetabulum (43). My first suspicions 

 of the inaccuracy of this arrangement were aroused by observino- 

 that in those figures of Pterodactyles given by H. v. Meyer in his 

 ' Rept. a. d. lith. Schiefer,' in which both ossa pubis (pirepubis) 

 are displayed in side or oblique view, the right or left bone (as the case 



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