i8S6.] Lucas on the Affiuities of Ckcstura. 44 S 



being placed in an order by themselves. They are a most 

 attractive group of birds for study, and all that I have examined 

 or seen figured offer good cranial generic characters, which is 

 moi'e than can be said for most birds. In the ensuing compari- 

 sons Trochilus mayhe construed as T". colnbris^whWe Chelldon 

 stands for C oythrogaster^ this bird having been chosen 

 simply because its name is a little less formidable than that of 

 most Swallows, and not from any peculiarity of its skeleton. 

 Before taking up the more salient structural characters, it may 

 be well to say that, viewed in profile, the skull of Chcetura is 

 very suggestive of Chordelles, while that of Chelidon urmiistak- 

 ably i-esembles that of a Flycatcher. The sphenoidal rostrum of 

 Chcettira is broad, the palatines are sepai'ated from one another, 

 and the pterygoids are in close proximity to the basi-temporal 

 region,* all characters wherein Chcetura agrees with Trochilus 

 and differs from Chelidon. This biixl has the rostrum narrow, 

 the palatines applied to each other posteriorly, and the pterygoids 

 standing well out from the basi-temporal region, as in the higher 

 Passerines. In Chivtura the curiously expanded end of the vomer 

 abuts on the maxillo-palatines, with which in young birds it is 

 intimately connected. While this is wholly unlike the sharp- 

 pointed, anteriorly free, vomer oi'Trochlhts., and more nearly re- 

 sembles the typically passerine vomer of Chelidon., yet the vomer 

 of Chelidon is quite free from the maxillo-palatines, although it 

 overlies them for its entire length. Now, among the Goatsuckers, 

 Choi'deiles has a slender, pointed vomer, which at first rests upon 

 and later in life coalesces with the united maxillo-palatines, while 

 in Antrostonius., and to a less extent in Nyctidroinus., the vomer 

 is broad and at its free extremity articulates with the maxillo-pala- 

 tines. Assuredly there is an interesting suggestion of relation- 

 ship between Chceticra and the Goatsuckers, and a study of the 

 embryology of the former bird would undoubtedly yield good re- 

 sults. The maxillo-palatines of Antrostomus terminate in recurved 

 points which bear a certain resemblance to the slender, curved 

 maxillo-palatines of Chcetura. In Chelidon these bones are ex- 

 panded at their free extremities, these expansions having the 



*Perhaps I over estimatethe importance of this last character, but it is a pronounced 

 feature of many 'Picarise,' notably of the Woodpeckers and Goatsuckers, less so of the 

 Cuckoos. 



