358 



DJl. E. W. SHrFELDT's MOEPHOLOGICAL 



On the Trachea, Visceral Anatomy, and other parts. 

 More for my own satisfaction than with the expectation of 

 revealing any structure that would prove to be different from 

 what we already know of the morphology of the trachea or other 

 parts in the Passerine birds, I examined the wind-pipe, its mus- 

 cular and associate parts, as I did the several organs in the 

 chest and abdomen of these American Swallows, but found 

 nothing that required to be specially noted here. 



The trachea exists as we find it in most true Passeres, as do 

 the several pairs of muscles at its lower larynx. I found the 

 " sterno -tracheal es " to be very delicately formed indeed, almost 

 of hair-like proportions in some of the genera, as in Progne. 



The gall-bladder is of good size, and the right lobe of the liver 

 the larger division of tliat organ. 



Caeca coli are present in Swallows, but are of almost rudi- 

 mentary proportions, and in some cases might be easily over- 

 looked. 



It is my intention to refer to a few of these points again, when 

 we come to consider the visceral anatomy of the Swifts and 

 Humming-birds. 



The Osteology of the Sirundinidce. 



Skeletons of representatives of all the Hirundinidw of the 

 United States are before me, and in sufiicient number, so that 

 a general definition for this part of the structure of these birds 

 becomes quite possible, and will be given here. It is my inten- 

 tion, however, to be brief in this matter, not only on account of 

 space, but in view of the information already given. 



Of the Shull. — When I came to compare and examine the 

 skulls of our seven species of Swallows, I was surprised to find 

 them presenting such striking differences in their general form. 

 Not but that they could each and every one of them be recog- 

 nized at once as skulls of Swallows, but rather that they possess 

 characters quite distinct and peculiar to the species, and there 

 would be no difficulty whatever in telling, for instance, the skull 

 of a Barn-Swallow from one of a Cliff-Swallow — so diverfee is the 

 general outline of each. 



In Progne suhis (PI. XXI. figs. 18, 19, and 20) we find a skull 



