890 DR. R. W. SHUfELDT ON THE OSTKOLOGY OF THE [DeC. 1, 



desmoguatlious, as in the Falconidse, and much more so than in the 

 Strigidse, which are ahnost schizognalhous. The palatine bones also 

 meet across the middle line for g of an inch, in a manner which is 

 quite peculiar, and can be best understood by a reference to the 

 drawing, each bone being apparently folded on itself behind the 

 point of junction with its fellow, and articulating with the hasi- 

 sphenoidal rostrum, as well as anchylosing with the vomer by its 

 inflected and upward-turned margin ; each developes a very short 

 slender anteriorly directed process close to the vomer, which 

 projects forwards on each side of it near its middle. 



"The vomer itself is a quarter of an inch long, slender and quite 

 blended with the palatines ; its anterior pointed extremity advances 

 as far forwards as the posterior border of the median palatine 

 symphysis mentioned above. 



" The posterior external angles of the palatines, so large in Capri- 

 mulgus and Podargus, are not developed. The basipterygoid facets 

 are large. In the eye the sclerotic ossifications are not considerable, 

 as in the Owls, being not at all unusually developed '. 



Among the American Nightjars the basitemporal area of the 

 skull is both broad and deep, A lip of bone usually shields tlie 

 double entrance to the Eustachian tubes, while the lower margins of 

 the auricular rims are produced well downwards. 



The condyle is small and of a hemispherical form ; the plane in 

 which the periphery of the foramen magnum lies makes an angle 

 with the plane of the basis cranii of about forty-five degrees. A 

 rounded notch is found in the medio-superior margin of the foramen 

 in Chordediles, which is not seen in the Whippoorwill. Tlie 

 supraoccipital prominence is barely pronounced ; it may be pierced 

 by a foramen in the middle line in some specimens of the Texas 

 Night-hawks. 



Huxley and Nitzsch have both called attention to the peculiar 

 conformation of the mandible in the Capriinvfgidte. This structure 

 is well to be seen in all of our American forms of the group, and is 

 shown in the drawing (Plate LIX. figs. 1, 2). The ligamentous union 

 between the dentary and paddle-shaped ramal portions is very slight, 

 and during the ordinary process of maceration of the skeleton of a 

 Nightjar this is one of the first points to give way — the jaw coming 

 apart in three pieces. 



The limbs of the hyoidean apparatus flare out in a fashion to 

 correspond with the general form of a Goatsucker's mouth. 



In Chordediles the basibranchials are in one piece, they being in 

 two in Nuttall's Nightjar. Both birds have the extremely slender 



^ A. H. Garrod, " On some points in the Anatomy of Sieatornis" (P. Z. S. 

 1873, pp. 526-33). speaking of the sclerotal plates of the eye, says, " I find that 

 they are quite small m the Caprimulgidce, although the circle they Ibrin is 

 comparatively a large one. In the Humming-birds they are about in proportion 

 with the size of the birds. Some of the Swifts, however, present rather an 

 unusual condition of these plates, the posterior ones being mucia tlie deepest, 

 which depth gradually diminishes, as we pass either way round to the opposite 

 side of the circlet, the middle anterior one being the narrowest plate of any ; 

 this feature is quite noticeable in some of the Swallows." 



