1889.] MR. W. K. PARKER ON STEATORNIS CARIPENSIS. 



163 



Classification of Birds was being written, I pointed out to Professor 

 Hnxley that even in the Gallinaceous tribes, which are, more than 

 any other birds, most distinctively " Schizognathous," the larger 

 Curassows, e. g. Grax ylohicera, are " Desmognathous." 



I have since that time discovered that Bicliolophus is directly 

 Desmognathous '. 



If we then bind up together some two dozen families of arboreal 

 birds of the higher, but not highest kinds, and call them " Coccy- 

 gomorphse," we must use the palatal character for just what it is 

 worth and no more. If all these troops are to march under the 

 Huxleyan standard, then we shall have the following palatal cha- 

 racters in this mixed multitude of birds : — 



ScHizoGNATHiSM. — Trochilidse, Trogouidae, Caprimulgidse (part.). 

 iEciTHOGNATHisM. — Cypselidse. 

 Desmognathism. — (a. Indirect) . — Coliidse. 



(6. Imperfect direct). — Capitonidse. 



(c. Perfect direct). — Rhamphastidse aud 



many others. 

 {d. Double). — Bucerotidse (part.), Steator- 

 nithidse, Podargidae. 

 Saurognathism -. — Picidse, Yungidse. 



So, again, with regard to another of the deep morphological cha- 

 racters, namely, the arrest or development of the " basipterygoids "; 

 in this character we have the extremest difference, for Steatornis is 

 almost Struthious in this respect, and Cuculus (amongst others) has 

 these parts aborted as much as in the Passeres, in wFiich they very 

 seldom show a trace in the adult. 



Another deep and diagnostic character is the peculiar articulation of 

 the centra of the vertebrae, between the axis and the sacrum ^. This, 

 as a rule, is what is called cylindroidal by Prof. Huxley, and hetero- 

 ccelous by the American ornithologists. Now it has long been known 

 that many Water and Wading birds have their thoracic or dorsal ver- 

 tebrae of the archaic type — like those of ancient reptiles, they are 

 opisthoccelous. But I long ago showed that Parrots have the same 

 structure, combined with an anticipation of the Mammalian centrum, 

 namely with terminal epiphyses. But more lately I have discovered 

 that the dorsals of Steatornis are opisthoccelous also. This fact has 

 softened down my objection to putting the Parrots along with the 

 other Zygodactyles and their Syndactyle relatives ; they are not more 

 isolated than the Humming-birds and the Swifts. The manner in 



' In my paper on the Bird's Skull, Linn. Trans, new series, Zool. vol. i. 

 p. 129, pi. XXV., I have described the palate of this bird as being imperfectly 

 desmognathous ; the bony vmion of the " maxillo-palatine plates " is, however, 

 perfect in my specimen. 



^ Strictly speaking the vEgithognathous and the Saurognathous palates are 

 merely varieties of the Schizognathous type ; that reduces the whole thing to 

 two main kinds — the Schizognathous and the Desmognathous; the "Dro- 

 mseognathous " condition is merely a retention in the adult of an early embryonic 



'^^ Proc. Eoy. Soc. 1888, pp. 465-482. 



