On the Osteology of Nyctosaurus. 149 



ing in a somewhat angularly expanded median symphysis, which is thor- 

 oughly co-ossified, and with an anteriorly directed, somewhat divergent, 

 flat, and obtusely pointed anterior process at each side, the continuation 

 of the posterior flattened portion which joins the pectineal process on 

 the everted margin of the pelvis. This process is somewhat thickened 

 at its posterior extremity, and is of about the same width as the other 

 parts of the bone. The bone in the specimen had been torn apart at the 

 symphysis, each half remaining in partial juxtaposition with the corre- 

 sponding half of the pelvis. As flattened out the conjoined bone is 

 much too wide transversely to articulate with the surfaces on the margin 

 of the pelvis; too wide even in the flattened-out position of these parts. 

 It seems certain that the extremities must have articulated with the 

 processes described, quite as I have already described the conditions in the 

 pelvis of Pteranodon, and it therefore follows that the bone in life must 

 have had a considerable convexity, in a broad, U-shaped form. 



There are no indications of any sutural connection in the bones of 

 the pelvis, except such as I have described with the sacrum and between 

 the two halves. Nevertheless, the presence of the large foramen, the 

 general shape of the bone and the position of the acetabulam would be as 

 one would expect were there really the three elements present. A suture 

 between the ischium and pubis is scarcely to be expected, in consideration 

 of the obliteration of the sutures elsewhere in the skeleton. I am there- 

 fore inclined to look with favor upon the view, long held by Seeley, that 

 the pelvis is of the normal reptilian structure, and that the bones in front 

 really do not belong to it. It seems very probable that the anterior pro- 

 longations of the prepubes come in contact with the posterior ends of 

 the parasternum, and that the whole bone is merely a continuation of the 

 abdominal armature. However, I must admit that the persistence of the 

 sacral and symphysial sutures, permitting the pelvis to drop apart without 

 distortion, and the utter obliteration of any ischio-pubic suture is 

 inexplicable. 



" Naturalists have been uncertain as to the number of bones in the 

 pelvis of pterodactyls, because the bones blend together early in life, as 

 in birds. Some follow the Amphibian nomenclature, and unite the 

 ischium and pubis into one bone, which is then termed ischium, when the 

 prepubis is termed the pubis, and regarded as removed from the 

 acetabulum. There is no ground for this interpretation, for the sutures 

 are clear between the three pelvic bones in the acetabulum in some 

 specimens, like Cycnorphamphus Fraasii, from Solenhofen and some 

 examples of Ornithocheirus from the Cambridge Greensand."* 



By modeling in cardboard and clay the bones of the pelvis and 



•Seeley, Dragons of the Air, p. 04. 



