Prof. H. G. Seeley on the Ornithosaurian Pelvis. 239 



of Wagner and Quenstedt. If authority went for anything, 

 I might mention that Professor Huxley, in his ' Anatomy of 

 Vertcbrated Animals,' 1870, adopted the view that the pubic 

 bone enters into the acetabulum and that the separate bone 

 is the prepubis as the more probable interpretation of the 

 pelvis. Till better specimens are discovered this condition of 

 the pelvis must rest upon the evidence in the museums at 

 Cambridge and Stuttgart. The absence of sutures in the 

 Munich specimens is of no more value as evidence of struc- 

 ture than the absence of sutures in the pelvis of an adult 

 bird. The sutures between the pubis and ischium and ilium 

 are seen in the imperfect examples of the innominate bones of 

 Ornithoclieirus preserved in the Woodwardian Museum. In 

 the ' Ornithosauria ' *, plate viii., I have drawn some of these 

 specimens ; and the explanation of fig. 1 (specimen 1, 

 tablet 10), is "Fragment of a large right os innominatum ; 

 the faint Y-shaped lines in the acetabulum indicate the limits 

 of the three component pelvic bones." In figure 2 (specimen 

 4 on tablet 10) that portion of the vertical suture between the 

 pubis and ischium is drawn which extends between the 

 obturator foramen and the acetabular border f- These speci- 

 mens therefore, if there were no others, demonstrate the 

 formation of the pelvic acetabulum by three constituent bones 

 and a vertical suture dividing the pubis from the ischium ; 

 and in my judgment they are conclusive that the pubis forms 

 the anterior side of the plate of bone below the acetabulum 

 not only in Ornithocheirus, but in Dimorphodon and all other 

 genera of Ornithosauria. The only complete specimen in 

 which the suture is seen between the pubis and ischium is the 

 fossil figured by Dr. Oscar Fraas as Pterodactylus suevicus, 

 which I regard as a new species. If the absence of sutures 

 in the Ornithosaurian pelvis were evidence that they had not 

 existed, there would be no justification for identifying the 

 ischium in the way which has been generally done ; and the 

 innominate bone might have been supposed to have been 

 unsegmented. This hypothesis is, however, as gratuitous and 

 contrary to fact as that which" Dr. Zittel adopts. It is not 

 that there is any a priori improbability in the exclusion of 

 the os pubis from the acetabulum, for this condition is one of 

 the generic characters by which the Sauropterygian genus 

 Colymbosaurus is defined. But in Ornithosaurs an independent 



* Published, I believe, in January 1870. 



t I have al^o figured the visceral aspect of a separate ischium, which 

 shows the suture with the ilium and a small portion of the vertical 

 suture with the pubis (tablet 10, no. 2, ' Ornithosauria,' p. 59, pi. viii. 

 fig. 4). 



17* 



