348 



DR. n. w. shufeldt's morphological 



distance and upon which they are gradually lost. These rug^e 

 are so well marked that they may be easily discerned from an 

 examination of the external surface of the stomach ; and upon 

 the dorsal aspect of the organ they seem to rise into a sort of 

 transverse ripple, a character present also in the Whip-poor-will. 

 The oesophagus is of large calibre in these birds, and, as stated, 

 thick and firm as it approaches the gastric pouch. 



The small intestine is delicately constructed, and not especially 

 large as it passes from tiie wall of the stomach at a point situ- 

 ated at the upper right side of the organ, not far from where the 

 oesophageal tube enters. 



Inside the stomach the gastric rugae are covered by a moderate 

 layer of corneous tissue, composing about one third the thickness 

 of the stomach-wall, which may best be seen upon a sectiun of 

 the organ. 



Of the Osteology. 



For the purposes of classification I gave in my first memoir 

 on the present subject (P. Z. S. 1885) sufficiently full descrip- 

 tions of the skeleton in specimens of Chordeiles and Phalceno- 

 ptilus Nuttalli for all that is required in the present connection ; 

 so it will be only necessary here to make some additional remarks 

 upon the skeleton as found in my sijecimen of Antrostomus. 

 Judging from the figure of the base of the skull of the common 

 European Nightjar, which I copied from Huxley and repro- 

 duced in my first memoir, I should say that, osteologically, 

 tiie American form of this bird was very much like it in that 

 particular system of its anatomy ; indeed, I expect that struc- 

 turally the two forms are very similar. Then, as one would 

 naturally have expected, I have found, upon a mere superficial 

 comparison, that osteologically the common Whip-poor-will and 

 NuttalFs Poor-will {P. Nuttalli) are very much more alike than 

 either of them resemble Chordeiles. In fact, it takes but a 

 glance at a skeleton of a true Whip-poor-will and a Nighthawk 

 to convince us at once of the marked difiereuces that exist 

 between them. As I have elsewhere said, these two genera of 

 Caprimulgine birds are separated structurally by very excellent 

 characters of a nature at once recognizable. 



Figures in the plates of my first memoir, above alluded to, also 

 illustrated the skull of a Chordeiles and the principal bones of 



