92 ON PALLAS' CORMORANT STEJNEGER AND LUCAS. 



diameter being nearly twice the vertical, while in carbo this foramen is 

 more pointed posteriorly, and narrower, the length being more than 

 three times the height. 



In consequence of the size of this foramen the distauce from the dor- 

 sal edge of the ilium to the ventral edge of the ischium is much greater 

 than in carbo. 



The bar of the ischium bounding the obturator space is sharp-edged, 

 rugose, and concave exteriorly on the posterior portion, while the cor- 

 responding portion of the ischium in carbo is comparatively smooth and 

 slightly convex posteriorly. 



The posterior border of the ischium is straighter than in carbo and 

 the iliopubic articulation one-third shorter. 



The femur is 5 mm longer than that of carbo, in every way much more 

 massive, and with all the muscular ridges more pronounced, while curi- 

 ously enough it is more pneumatic, having several foramina in the 

 ventral aspect of the neck that are lacking in carbo. 



There is nothing to distinguish the femur of urile from one of dilo- 

 phus of the same length, and of the two that of dilophus is slightly the 

 heavier. 



But in the specimen of urile in which the humerus corresponds in 

 length to that of dilophus, the femur and tibia are both longer and 

 heavier than in dilophus, and the tarsus a little lighter. 



The phalanges, again, are more massive in urile than in dilophus. 



The smallest of the three tibise is slightly longer than that of carbo, 

 the cnemial crest is more expanded, and the cuemial ridges farther apart 

 an I more pronounced. 



The distal extremity of the tibia is also wider than in carbo, but at 

 its smallest diameter the shaft is no larger. 



The muscular ridges and grooves are more marked than in carbo, but 

 in the absence of more material and making due allowance for individ- 

 ual variation, it is difficult to point out characters which definitely dis- 

 tinguish the tibiae of the two birds. 



The tarsus is of the same length as in carbo, but much wider, and, as 

 throughout, with all the ridges more pronounced. 



Little can be said concerning the three cervical vertebrae, except that 

 unlike the other bones they are less strongly built than the correspond- 

 ing boues in carbo. 



From the foregoing notes it will be seen that the differences existing 

 between corresponding bones of perspicillatus and carbo also exist be- 

 tween the same bones of urile and dlophus, and that conversely perspi- 

 cillatus and urile agree with one another as do carbo and dilophus. 



The sub genera Phalacrocorax and Urile, therefore, seem to rest on 

 good structural foundations, each being characterized by internal as 

 well as external characters. 



Unfortunately no skull of perspicillatus is to be had, but the crania 

 of carbo and dilophus agree with one auother, while differing strikingly 

 from the cranium of urile. 



