THE ANATOMY OF BIBDS.— OSTEOLOGY. 



171 



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bine birds (Peristeromorj^hre of Huxley's arrangement) : niaxiUo-]>alatines elongate and 

 spongy; basipterygoid proecsses narrow, but prominent, (b) The gallinaceous birds (^iec- 

 toromorpha:) : maxillo-palatines varying greatly in size, but always lamellar ; palatines long 

 and narrow, wdth rounded ofl' poslercj-external angles ; basipterygoid processes oval, flattened, 

 sessile upon the rostrum, articulating with the pterygoids, (c) The penguins (Sphenisco- 

 morphce) : maxillo-palatines concavo-convex and lamellar; no basipterygoid processes; ptery- 

 goids flattened, (d) In the gulls, petrels, loons, grebes, 

 and auks, constituting tlie Cecomorpha; of Huxley, the 

 maxillo-palatines are usually lamellar and cfuicavo- 

 convex, but may be spongy, tumid, and closely approx- 

 imated to the vomer; and basipterygoid processes are 

 absent or present, (e) In the cranes, rails, and their 

 allies (Geranomorphce), the maxillo-palatines are con- 

 cavo-convex and lamellar, and basipterygoid processes 

 are usually absent. (/). In the plover-snipe group, 

 or limicoline Grallas (^Cluiradriomorphte) , the maxillo- 

 palatines are always concavo-convex and lamellar ; the 

 basipterygoid processes narrcjw and prominent. Except- 

 ing perhaps group d, which does not hang together so 

 well, the schizognathous groups here noted correspond 

 very closely with recognized orders or suborders oi Ijirds; 

 in all of them, the maxillo-palatines are perfectly dis- 

 tinct from one another and from the vomer, and the 

 latter is slender and usually pointed. There are plenty 

 of other birds in which the former factor in the case 

 obtains ; but in these the vomer is broad and usually 

 truncate in front (see JEyithognathism, beyond). 



Desmognathlsm (Gr. Sea-fios, desmof>, a bond) is 

 exhibited in one or another style by those swimming 

 and wading birds which are not schizognathous, by 

 the birds of prey, and various non-passerine perching 

 birds. It does not fadge so well as any other one of 

 the palatal types of structure with recognized groups of 

 birds based on other considerations. In the "bound- 

 palate " type, the vomer is either abortive, or so small 

 that it disappears ; when existing it is usually slender 

 and tapers to a point in front ; the maxillo-palatines 

 are united across the median line, either directly or by 

 means of ossifications in the nasal septum ; the posterior 

 ends of the palatines and the anterior ends of the ptery- 

 goids articulate directly with the rostrum (as in schizo- 

 gnathism). This type is simply and perfectly exhibited by a duck (fig. 78) in which the 

 maxillo-palatine is a broad flat plate united with its fellow in mid-line ; the oval sessile basi- 

 pterygoid facets are far forward, opposite the very ends of the pterygoids. In the flamingo, 

 ibis, spoon-bill, stork, heron, the united maxillo-palatines are tumid and spongy, filling the 

 base of the beak ; basipterygoids are wanting (rudimentary in the flamingo). In totipalmate 

 swimmers (pelican, cormorant), desmognathlsm is carried to an extreme by union of the palate 

 bones also across the mid-line ; the general arrangement is as before. The birds of prey 

 exhibit several special conditions of desmognathlsm. The pan'ots are another case ; among 



Fig. 78 — Deamotjnatlwus skull of mal- 

 lard (luck. Anas hoscas, nat. size, froni 

 nature, by Dr. E. W. Sbufeldt, U. S. A. 

 Letters as before. 



