292 



BARON NOPCSA ON THE SUPPOSED 



[June 6, 



This highly remarkable coincidence suggests the probability that 

 the bone in question represents an asymmetrical but nevertheless 

 unpaired organ. 



So far as I am awai'e thei'e is no known i-eptile, living or 

 extinct, in which the clavicle is bifui'cated at one end. Moreover, 

 in most terrestrial and aquatic reptiles, when clavicles ai'e present 

 there is also an interclavicle, which has never been found in 

 Sauropoda. It must also be remembei'ed that these large 

 hei-bivorous Dinosaurs were probably descended from the carni- 

 vorous Theropoda, which are always destitute of a clavicular 

 arch. 



Text-fig. 49. 



I, .^ 



Os penis of European Otter. 



I am therefore of opinion that the problematical bone of 

 Biplodocus in question cannot be a clavicle, and it is necessary 

 to consider Hatcher's alternative suggestion that it is an os 

 penis. 



The fact that existing birds and reptiles are destitute of an os 

 penis does not necessarily imply that gigantic reptiles like 

 Dijylodocus similarly lacked the bone. Among Mammalia it is 

 well known that the element occurs only sporadically, being 

 present, for instance, in the Anthropoid Apes and absent in Man. 



Among the living reptiles we know two types of genital oi-gans. 

 The Squamata show what may be called a bifid penis, while the 

 Orocodilia and Ohelonia have the penis simple exterioi'ly, with a 

 corpus fibrosum and freqviently even a glans penis well developed. 



