172 



GENERAL OBNITHOLOGY. 



other cranial characters of these birds is to be noted the articulation of the palate bones with 

 the upper beak, like that of the zygoma. The multifarious Picarian birds, or non-passerine 

 Insessores, are desmognathous, excepting the schizognathous trogons (Trogonidai) and the 

 " saurognathous " woodpeckers. Parker has established the following categories of desmo- 

 gnathism : (a) Perfect dh-ect, the maxillo-palatines uniting below at the mid-line ; either with 

 the nasal septum free from such bony bridge, as in a duck; or anchyloaed therewith, as in many 

 birds of prey. (6) Perfect indirect, very common, as in eagles, vultures, owls; maxillo- 

 palatines separated from each other by a chink, but an- 

 chylosed with nasal septum. (c) Imperfectly direct; 

 maxiUo-palatines sutured together, but not anchylosed. 

 " In young falcons and hawks the palate is at first in- 

 direct, is then imperfectly direct, and at last perfectly 

 direct." ((f) Im/perfectty indirect; maxillo-palatines 

 closely articulated with, and separated by, the " median 

 septo - maxillary ;" but there is no anchylosis. (e) 

 Double : the palatines united as well as the maxiUo- 

 palatines ; as in the pelican and cormorant above noted, 

 in certain Caprimulgine birds, hom-biUs, etc, (/) Com- 

 pownd: when the properly cegithognathous skuU of a 

 passerine bird becomes also desmognathous. 



\Jfrry^A^ 



-SI 



>s:githognatIiism (Grr. alyiBoKos, aigithalos, some 

 small bird) is exhibited almost unexceptionally by the 

 great group of Passerine birds ; it is also nearly coinci- 

 dent with Passeres, though a few other birds, notably 

 the swifts (CypseUda), also exhibit it. Huxley's term 

 Coracomorphee, nearly synonymous with Passeres, relates 

 to the palatal structure exhibited by a raven (fig. 79), as 

 typical of that of Passeres at large. The vomer is a 

 broad bone, truncate in front and deeply cleft behind, 

 embracing the sphenoidal rostrum in its forks. The 

 palatines have produced postero-external angles. The 

 maxillo-palatines are slender at their origin, extending 

 inwards and backwards over the palatines and under the 

 vomer, where they end free, being united neither with 

 each other nor with the vomer. This disconnection of 

 the maxillo-palatines is quoad hoc " schizognathous,'' of 

 course ; but such condition, in association with the pecu- 

 liarities of the vomer, is aegithognathous. The nasal 

 septum in front of the vomer is often ossified in Begitho- 

 gnathism, and the interval between it and the premax- 

 illffi filled up with spongy bone; ,but no union takes 

 place between this ossification and the vomer (Huxley). 

 According to Parker, the distinguishing character of the 

 aegithognathous type is the union of the vomer with the alinasal wall and turbinals. He dis- 

 tinguishes four styles : (a) Incomplete; very curiously exhibited by the low Twrniai, which 

 stands near the gallinaceous birds. (6, c) Complete, as represented under two varieties, one 

 typified by the crow, an Oscine Passerine, the other by the Clamatorial Passerines Pachyrham- 

 phus and Pipra. {d) Compmmd, i. e., mixed with a kind of desmognathism, as noted above. 

 " Vomer truncated in front " is the general expression for the condition of that bone in the 



Fig. 79. — ^githognatluMS ekuU of 

 raven, Corvus corax, nat. size, from na- 

 ture, by Dr. E. W. Shufeldt, U. S. A. 

 Letters ae before. N. B. The reference 

 line, J', goes to the ossified nasal Beptum 

 borne upon the end of the vomer, which 

 latter bone begins at the thiclcest part of 

 the central projection. Mxp underlies V 

 and overlies PI, but touches neither. 



