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



the subclass or order that the fracture would sometimes take 

 place on one side onlj and that sometimes fragments of the 

 broken bone would remain in contact with the part of the 

 pubis with which it is supposed to have been continuous, 

 while the prepubic elements might also be expected to show 

 evidence of iracture ; but there is no specimen in which a 

 recognizable portion of the element termed prepubic is seen 

 coossified with the pubic bone ; and even when the pelvic 

 sutures between the other bones are preserved there is no 

 evidence of fracture, but sharply defined separation of these 

 prepubic ossifications from the pubic bones, as in the specimen 

 of Cycnorhamphus at Stuttgart. 



The bones, even when not anchylosed together, have usually 

 remained in nearer contact with each other than with the pubic 

 bones: and this seems to me better consistent with separate 

 ossification than with fracture. Moreover they always show 

 forms and proportions which suggest complete ossifications ; 

 and tliis does not seem to be evidence to support the hypo- 

 thesis that these bones are fractured portions of the pubis. 



The following facts contribute towards a clearer conception 

 of the pelvis. 



If we examine a specimen like that named PterodactyJus 

 grandipelvis (von Meyer, 

 Kept, lithog. Schiefer, T. viii. 

 fig. 1) it is manifest that the 

 sacrum widens anteriorly in the 

 transverse direction (fig. 1). 

 The same character is shown 

 in a sacrum of Rhamphocepha- 

 lus from the Stonesfield Slate, 

 in the collection of the Rev. 

 P. B. Brodie, F.G.S. It is at 

 present uncertain whether tlie 

 character is common to all 

 Ornithosauria. From this con- 

 dition of the sacrum it follows 

 that since the bones in the 

 ischiac region of the pelvis 

 approximate towards each other 

 closer than those in the pubic 

 region, the pubic bones cannot 

 meet in a median symphysis 

 unless they are longer than the 



Fiff. 1. 



ischia, which, 

 never the case. 



I submit, is 



Pt. grandipelvis. 

 (Meyer, /. c. T. viii. fig. 1.) 



I would next direct attention to the Munich specimen named 



