338 



STRUCTURE AND CLASSIFICATION OF BIRDS 



at the beginning of the neck ; on the breast each half gives off 

 a strong lateral branch. 



All the Charadriidse, and indeed all the Limioolse,' are schi- 

 zognathous ; but many of them have not the typical condition 

 of the vomer which accompanies as a rule the schizognathous 

 skull. In the woodcut (fig. 169) a few exceptions to this are 

 given, which range from the typical 

 condition observable in Sterna to an 

 excavated extremity, such as charac- 

 terises Becurvirostra. In Chionis the 

 vomer ends in the typical manner, i.e. 

 in a point ; but it is exceedingly broad 

 before its termination, and therefore 

 quite unusual. 



In Thinocorus and Attdgis the 

 vomer is short and broad, and almost 

 passerine in form. 



The maxillo-palatines are, as a 

 rule, thin and scroll-like plates, which 

 are bent downwards and often defi- 

 cient in ossification, leaving holes here 

 and there. The palatines have a 

 spout-like process, extending upwards 

 towards the base of the skull, which 

 is especially well marked in (Edicne- 

 mus. The Limicolae are nearly all of 

 them schizorhinal, the delicate bar of 

 the premaxilla being inserted at a 

 different plane from the attachment 

 of the nasals to the frontals. In the 

 Charadriidae proper there are a pair of 

 largish occipital vacuities, one on either side of the foramen 

 magnum. These same birds have basi-occinital processes. 



Fio. 168. -Undee View op 

 Skull of Charadrius pluvi- 

 alis (afteb Huxley). 



Pinx, premaxilla ; Vo. vomer ; Mx, 

 maxilla ; PI, palatine ; R. ros- 

 trum ; JVa, nasal ; Ma;p, maxillo- 

 palatines ; * ectetbmoid. 



' Shufeldt (' Contributions to the Comparative Osteology of Arctic and 

 Subarctic Water Birds,' J. Anat. Phys. 1889 and 1890) figures a few skulls of 

 Limicolffi. See also the same, ' On Aphriza virgata,' Juurn. Morph. ii. p. 311. 

 See also ' Osteology of Numenms,' &o., Journ. Anat. Phys. 1885, p. 51 ; 

 ' Observations on the Osteology of Podasooys montamis,' ibid. 1884, p. 86. 



