﻿260 SHUFELDT. 



A casual glance at the skeleton of either Sarcops calvus or S. melano- 

 notus is sufficient at once to satisfy the osteologist that it possesses all 

 the general characters of a typical representative of the passerine group 

 of birds, with many special ones that bring it very close to the forms in 

 that assemblage more or less nearly related to the corvine type, and that 

 it bears a somewhat similar relationship to Corvus or Pica as do the 

 icterine genera mentioned above. These characters are immediately to 

 be recognized in the skull, the bones of the pectoral arch, the sternum, 

 and the pelvis — and, when this is the case, it is fair to presume that the 

 vertebral column, the ribs, and the skeleton of the limbs form no 

 exception. 



The skulls in Sarcops calvus and S. melanonotus practically agree in 

 all particulars, and to such a degree that it would be difficult to distin- 

 guish one from the other even in a long series of specimens. In making 

 such comparisons the fact must be borne in mind that there may be 

 marked differences in the skulls of different individuals of the same 

 species, a good example of which I long ago pointed out in the case of 

 Xanthoceplialus? 



THE SKULL. 



Viewing the skull of Sarcops calvus upon its superior aspect, it presents 

 one very characteristic feature. This consists in the deep median fur- 

 row extending from the cranio-facial line backwards to be lost on the 

 smooth, globular vault of the cranium in the parietal region. It is 

 deepest between the midsuperior points of the orbital peripheries, and 

 is due to the swollen condition of the latter, this being caused by the 

 diploic tissue in the frontal bones in this locality. jSTo such state as 

 this is to be found in any of our icterine birds, or in the crows; it is 

 entirely absent in Oriolus chinensis, and probably in other orioles. How- 

 ever, in some American forms of this genus, as in Icterus cucullatus sen- 

 netti, a shallow median depression may occur in the antero-frontal region, 

 but without a thickening of the orbital rims upon either side. It seems 

 quite likely then that this character alone would be sufficient to distin- 

 guish the skeleton of Sarcops from any of its near allies unless, perad- 

 venture, it be present in Goodfellowia, a species not yet examined by me 

 osteologically. Sarcops has the parietal region of the skull smooth, 

 full, and rounded, indicating a greater cranial capacity than in other 

 icterine species of similar size, as for example, Oriolus chinensis. In 

 this particular it approaches the crows and American marsh blackbirds 



3 Shufeldt, R. W.: Individual variation in the skeletons of birds, and other 

 matters. The Auk. July, 1887, 4, 265-268. (Letter to the Editor.) The two 

 skulls illustrating this letter have appeared in several of my memoirs; the speci- 

 mens themselves, however, are no longer in my collection, but were disposed of 

 either to the British Museum or to the College of Surgeons (Lincoln's Inn. 

 Fields), London. 



