1887.] 



On the Os Pubis in Crocodilia. 



235 



December 8, 1887. 



Professor Gr. Gr. STOKES, D.C.L., President, in the Chair. 



Mr. William Whitaker was admitted into the Society. 



The President announced that he had appointed as Vice-Presi- 

 dents — 



The Treasurer. 

 Sir William Bowman. 

 Dr. Frankland. 

 Sir G. H. Richards. 

 The Earl of Rosse. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. " On the Bone in Crocodilia which is commonly regarded as 

 the Os Pubis, and its representative among the Extinct 

 Reptilia." By H. G. Seeley, F.R.S., Professor of Geo- 

 graphy in King's College, London. Received October 24, 

 1887. 



Normally three elements enter into the construction of the pelvic 

 girdle, each of which unites with the other two, and contributes to the 

 formation of the acetabulum for the femur. The ilium and ischium 

 are always more or less ossified, but sometimes the pubis remains 

 represented by cartilage throughout life. Among the Amphibia the 

 pubis is often in this cartilaginous state in its living representatives, 

 so that only two bones and a cartilage usually contribute to form the 

 articular cup for the femur. Among Urodeles the pubic cartilage is 

 perforated by a foramen, which corresponds with the foramen in the 

 ossified pubis of a lizard, and appears to carry the obturator nerve ; so 

 that its identification with the pubis is established. But the pubis and 

 ischium are often connate ; by which term I designate that embryonic 

 state in which no division of the primitive cartilage into separate 

 elements has occurred. It is not quite so evident that the similarly 

 placed cartilage in certain Anura is homologous with that of Urodeles, 

 since it is not perforated in the same way ; and it becomes smaller in 

 aged specimens by the ischium encroaching upon it. It is absent in 



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