1887,] PKOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 377 



This collection was origiually presented by me to the Zoological 

 Society of London, and my remarks about it were intended for their 

 "Proceedings," but having learned from the society that they make no 

 attempt to form a museum, the character of my contribution was very 

 properly adjudged unsuitable, and I withdrew it. 



It is with pleasure that I now present it, in our joint names, Dr. 

 Streets' and mine, as a contribution to the anatomical collections of the 

 TJ. S. ^National Museum, where in reality it more properly belongs. 



In my remarks about them I will designate those by a (*) which I 

 have figured in the manuscript referred to. 



Skulls of Urinator lumme.* — These specimens do not materially differ 

 from others that I have examined coming from different parts of the 

 world. They well illustrate, however, a point previously referred to by 

 me in some other connection, which, for the moment, I do not recall, 

 and that is, in comparing skulls of the same species in any series of 

 vertelwates we are sure to meet with very interesting individual dif- 

 ferences. Upon viewing these two skulls from above, we observe that 

 in the larger one the supraorbital "glandular depressions" are much 

 more sharply sculpt, while the bony ridge dividing them, in common 

 with the median longitudinal ridge separating the crotaphyte fossae 

 behind, is sharp and thin, it being considerably broader in the smaller 

 skull. Again, in the hi.rge skull the post-frontal processes project 

 nearly directly outwards, while in tbe other specimen these apophyses 

 are curved so as to point almost directly downwards. This difference 

 can be better isppreciated by viewing these two skulls from behind. 



Eegardiug them upon lateral aspect, the chief feature to be noted is 

 that both have a very large subcircular vacuity in the iuterorbital sep. 

 tum, and a fairly large one connecting the foramina for the exit of the 

 second pair of cranial nerves. These two vacuities are in the larger 

 skull well separated, while in the smaller specimen they all but merge 

 into each other. 



Viewed from behind, we find the condyle proportionately larger in 

 the larger skull, and the skull of the smaller individual exhibits on 

 either side of the " supraoccipital prominence " a small vascular fora- 

 men, with a vertical groove leading downwards and outwards from each, 

 the prominence itself being perforated by a similar foramen in the me- 

 dian line. All of these apertures are absent in the skull of the larger 

 bird. 



Turning to the under side of these skulls we find but few decided 

 differences worthy of comment. In each the vomer is deeply cjarinated 

 beneath, with a sharp spine terminating it in front, while in other par- 

 ticulars this element is very much as we find it in the Larulw. The 

 pterygoidal heads of the palatines behind curve outwards in either 

 specimen, and those bones do not touch each other in. the median line 

 beneath the sphenoidal rostrum in this locality. 



