Prof. H. G. Seeley on the Ornithosaurian Pelvis. 245 



Cycnorhamphus Fraasii. In the drawing, which I copy from 

 my note-book, it is manifest that the pubis and ischium are 

 closely comparable with the same bones in {Pterodactylus) 

 dubius, except that a thin osseous plate extends backward 

 from the anterior thicker part of the pubis, so as to fill in 

 much of the deep notch which in Pt. dubius appears to divide 

 the pubic and ischiac bones, and which would otherwise be 

 seen in Cycnorhamphus Fraasii. It will also be seen that the 

 ventral border of the ischium is straight, and I suggest that 

 these straight borders not improbably met in a median sym- 

 physis. Still they are not thickened at the ventral border, as 

 is usual in a median union; but then there is a like condition 

 in Crocodiles in the borders of the ischia which are in median 

 contact. If the ischia converged ventrally at all, the narrow 

 posterior width of the sacrum shows that they must have had 

 a median union. The shortness of the pubis similarly shows 

 that no median union of the ventral margins of those bones 

 could take place. But if the thickened anterior ventral end 

 of the pubis is compared with the stalk of the prepubic bone, 

 a suggestive correspondence in size of the two parts is seen j 

 and I regard the two bones as having been in articular con- 

 tact, so that the prepubic bones made an anterior median 

 ventral symphysis corresponding to that usually made by the 

 pubes. This interpretation is not easily harmonized with 

 that offered by Quenstedt without adopting his hypothesis 

 of displacement of the pubis in Cycnorhamphus suevicus, 

 always supposing that the tubercle to which he believes the 

 prepubic bone to have been attached really carried that 

 element in the skeleton. 



The value of evidence in this matter of the nature of the 

 prepubic bone depends partly on its cumulative character. I 

 therefore transcribe the following memoranda from my note- 

 book on specimens at Munich. 



Fig. 5. Fig. 6. 



°=0 



Pterodactylus longirostrin. Pt. micronyx. Pt. micronyx. 



(Meyer, I. c. T. ii. fig. 1 .) (Id. ibid. T. iv. fig. 5.) (Id. ibid. T. iv. fig. 4.) 



In Pterodactylus vulturinus (Wagner) the antero-posterior 

 extent of the pelvic bones is 3-^ inches. The sacrum con- 



