900 DR. R. W. SHUFELDT ON TH F. OSTEOLOGY OF THE [DeC. 1, 



In Tachycincta thalassinu, as a representative of the Swallows 

 (fig. F), we find the broad vomer ( Vo) doubly notched in front, 

 whereas in a skull of Oroscoptes montanus, as a typical Passerine, 

 there is but one such notch ; otherwise in its relations, as well as the 

 hair-like maxillo-palatines with their backward-turned bulbous ends 

 touching each other in the median line, these several elements are 

 essentially similar. 



Moreover, we can easily see the evident middle place the palatines 

 of this violet-green Swallow hold, both as to their form and arrange- 

 ment, between the Swifts and more typical Passeres. 



Such a serial resemblance in gradation is again beautifully exem- 

 plified in the mandibles of these birds. In Paiiyptila both the angular 

 processes and the ranial cavities are missing ; tiiey are both fairly 

 well developed in the Swallow, while in most true Passeres they are 

 a decided feature. 



Of course there is but little or no resemblance between the man- 

 dible of a Swift and of a Humming-bird. 



What I have said about the mandibles of these several forms applies 

 with equal truth to the hyoidean apparatuses ; in all, the first and 

 second basibranchials are in one piece, and the elements of the giosso- 

 hyal portion remain in cartilage throughout life. 



Of the remainder of the Axial Skeleton in Trochilus. — One cannot 

 well study the spinal column of Alexander's Humniing-i)ird without 

 the aid of a strong lens ; the writer was obliged to bring to his assist- 

 ance a microscope armed with a 2-inch objective. By the help of 

 this instrument I count 13 vertebrae in the cervical region before we 

 come to that one which bears the leading pair of free ribs. In the 

 middle of the series these develop very long postzygapophyses, and 

 the finest imaginable parial parapophyses. 



The neural spines are nearly entirely suppressed throughout the 

 series, while the fifth, sixth, seventh, eighth, and ninth contribute to 

 form the carotid canal. After these a strong median hypapophysis 

 is found on each segment. 



The articulation of the centra are heterocoelous. Freely suspended 

 ribs are found upon the 14th and 15th vertebrae, the last pair having 

 epi pleural appendages. 



The 16th vertebra has a fully developed pair of ribs, which are 

 the first to connect with the sternum by costal ribs. This vertebra 

 is characterized by a low neural spine and single long median hyp- 

 apophysis. 



The I7th vertebra also possesses perfect ribs, and in it the hypapo- 

 physis is not so prominent, and the neural crest is still inconspicuous. 

 Strange to say, the I8th and 19th vertebrae, with complete ribs 

 reaching the sternum by haetnapophyses, are thorouglily anchylosed 

 with the pelvic sacrum, having their neural spines and hypapophyses 

 merged into each other as common superior and inferior crista 

 respectively. The former soon subsides upon the dorsal aspect of 

 the sacrum, while the latter is met by a transverse crest developed 

 by the 21st vertebra, beyond wliich it subsides over the body of the 

 23rd vertebra. This arrangement forms a crucial raised crest on 



