^°'i9i^^'] Shufelut, Osteology of Orthorhamphiis magnivostris . 3 



The point here to be noticed, however, is that they are, among 

 others, deep in Larus and oth^ Gulls, and in probably other 

 typical longipennine birds, in ^1 of which they approach each 

 other mesially, having but a small interval between them, while 

 in Chiornis, Plovers, and the Oyster-catchers [Hcematopns) they 

 are restricted in area and situated laterally. 



Passing forwards to the parietal region or vault of the cranium, 

 it is to be noticed in Orthorhamphus that there is here a rounded, 

 median, longitudinal groove, extending from the supra-orbital 

 glandular depressions backward to a level area, just beyond the 

 interval between the crotaphyte fossae. This groove is prac- 

 tically what is found, too, in the Laridce and others, while it is 

 almost entirely absent in Chiornis, Hcematopus, and others, and 

 quite so in most Plovers. In these latter birds there are no 

 " parietal eminences," which are well marked in Orlhoy/iamphus, 

 Larus, and in some other Gulls, but not in all, as they are absent 

 in Rissa, a species in which only the lateral boundaries of the 

 aforesaid median groove are elevated. 



From the parietal region forwards, to include the remainder 

 of this aspect of the skull, the characters vary in no small degree 

 throughout all of these genera of birds. In Orthorhamphus the 

 vaults of the orbital cavities are considerably raised above the 

 mesio-frontal area of the skull, and, omitting either lacrymal bone, 

 the free margin of each is notably sharp, and continues to be so 

 to the very apex of the post-frontal process. The orbital roof 

 on either side is perforated by a few scattered and minute 

 foramina, and these are far less evident in (Edicnemiis, while in 

 Squatarola sqiiatarola they are confined to a circular foramen of 

 some size, on either side, being situated well within the orbital 

 margin just beyond the parietal region of the cranium. In most 

 Gulls these foramina again are small and scattered, while in 

 Chiornis and the Oyster-catchers they are arranged in a row upon 

 either side and well within the orbital margin. As I have else- 

 where shown, they vary considerably throughout the Limicolce* 



In the mesial area of the frontal region of the skull of our 

 subject, on this its dorsal aspect, there is to be seen the very con- 

 character of the " crotaphyte fossa; " in the skull figured. It will be 

 observed that these concavities are nearly absent in Gallus, Coccothraustes, 

 Columha, Parva, and Pedionomus, while they are separated by a large 

 interval in Niimenius and Otis tarda, coming more or less closer together 

 in Larus, in the Great Auk, and in Daption. 



* Shufeldt, R. W., " Osteology of Numenius longirostris, with Notes upon 

 the Skeletons of Other American Limicolce," Journ. Anat. and Phys., Lond 

 Oct., 1884, pp. 57-82, Plates IV., V. (see Plate V., fig. 16). this paper 

 describes and compares the characters of a number of limicoline birds, which 

 descriptions will repay examination in connection with what is set forth in 

 the present contribution. 



Coues, Elliott, " Birds of the North-West, " Govt. Printing Office, Washing- 

 ton, D.C., 1874, pp. 592-602. We have here a brief, though good, account 

 of the osteology of the LaridcB, wherein the superior frontal regions of the 

 skull in several genera of the Longipenncs are compared, and the facts noted 

 may, with advantage, be taken into consideration with the present study 

 of the skull of Orthorhamphus. 



