350 STRUCTURE AND CLASSIFICATION OF BIRDS 



but the supra-orbital impressions are present. The maxillo- 

 palatines are very far apart, and besides being short are 

 swollen instead of being leaflike plates. The same pseudo- 

 holorhiny that characterises the Glareolidse is also found in the 

 present family. Five ribs reach the sternum. The coracoids 

 are quite separate at their insertion on to sternum. The 

 muscular formula of the two genera is the complete one 

 ABXY + . 



In Tliinocorus rumicivorus the syrinx has a pair of 

 lateral muscles, which are attached to the fourth incomplete 

 ring when seen from in front. This is probably the first 

 bronchial, the last three tracheal rings being thus incomplete. 



Glareola, Cursoriiis,Plnvianus,a.ndDroinas, all Old-World 

 genera, are included in a separate family, Glareolidae, which 

 GAEEOD regarded as very near akin to the Thinocoridse. 1 As 

 in them, basipterygoid processes and occipital fontanelles are 

 absent, and impressions of supra-orbital glands present. The 

 muscle formula too is complete, and the syrinx has intrinsic 

 muscles. 



Except in Cursorius there is a hallux. FORBES, with 

 some reason, has united into a group Pluviales, equivalent to 

 the rest of the Limicolae, this family, together with the Thino- 

 corida3 and Chioniclidse, mainly on account of the above 

 combination of skull characters found in no other Limicolae. 



As in them also there is pseudo-holorhiny, the bony 

 nostrils, though extending back beyond the nasal process of 

 the premaxilla, being distinctly rounded off. 



Pluvianus, however, has typically holorhinal nostrils. 



In Cursorius the grooves for nasal glands are converted 

 into elongated foramina by a fusion between adjacent pro- 

 cesses of the skull. 



The gulls form another distinct family, Laridae, containing 

 the genera Larus, Lestris, Sterna, Rhynchops, Aiwus, and 

 Gygis. 



The skull is schizorhinal and schizognathous, without 



1 LINN.T.US placed Glareola in genus Hirundo, SUNDEVALL in Caprimulgidoe. 



