HOLLAND: THE OSTEOLOGY OF DIPLODOCUS MARSH 263 
the marked differences which exist in the two specimens, which are so great as 
to make it appear, that, wherever located in the skeleton, they must have held 
opposite, or, at least, very different positions, but the fact, that, so far as is 
known to the writer, there is no record in any museum, or in all of the literature 
of the subject, of the existence of an os penis among any of the reptilia, living or 
extinct, whereas clavicles are found in many reptilian genera. The similarity of 
these bones to the os penis of Lutra, which is pointed out by Baron Nopsea, is 
curious, but entirely fails to carry conviction with it to my mind, and more partic- 
ularly since I have carefully reéxamined the original specimens which are in my 
custody. The fact of the bifidity of the penis of Struthio, which is pointed out by 
Baron Nopsca, does not appear to the writer to possess great weight. The tracing of 
resemblances between the struthious birds and the dinosauria appears to the 
writer, as he knows it does to others, to be in danger of being greatly overdone. 
Bifidity in the penis is characteristic of the organ in many widely different groups 
of animals. 
There is another thought or suggestion which has presented itself to the mind 
of the writer during his studies, namely, that these bones may possibly have been 
sternal ribs connected in some way by strong cartilaginous or ligamentary attach- 
ments with the roughened and thick ends of the sternal plates, or imbedded in 
cartilaginous or fibrous muscular tissues which do not exist in a fossil state in our 
specimens. In this connection reference may be made to the sternal ribs obtained 
with a skeleton of Brontosaurus, which Professor Marsh has figured in his work 
upon the Dinosaurs.’ It is worthy of note that the length of the longest and most 
attenuated of these bones is almost identically that of the supposed clavicle described 
by Hatcher. It is furthermore inconceivable to the writer that there should have 
been no sternal ribs in Diplodocus. ‘There must have existed a system of central 
supports for the lower part of the wall of the huge thoracic cavity. 
The attempt. to assign these bones to a position in which they may function as 
clavicles is not wholly satisfactory to the writer. To regard them as ossa penis is to 
the writer a far more thoroughly unsatisfactory hypothesis, as it was to his col- 
league, Mr. Hatcher, who first suggested it. The conclusions of my friend Baron 
Nopsea, reached in a labored argument based upon seven propositions, the first five 
of which bear only indirectly upon the subject, and the last two of which are posi- 
tively incorrect, are in the judgment of the writer untenable. The true position of 
these bones is still in doubt, and having left the reproduction of them for a few 
days in the position to which I had tentatively and experimentally assigned them 
7“*Pinosaurs of North America,’’ p. 171. 
