1922.] Characters III some C I laradr'iine genera. 489 



absence of an anterior foramen leadino; to tlio nasal reoion 

 liad their primal origin in function or lial)it. Is there a 

 single known morphological structure which has not the 

 same origin, even such deep-lying ones as the vomer, palate, 

 maxillo-palatine, or pterygoids, selected by Huxley for his 

 system of avian classification ? But when (to take one of 

 the characters already noticed in the text) we find a certain 

 type of nasal gland and a certain method of lubricating the 

 Schneiderian membrane characteristic of a Wader-form like 

 Pluvialls apricarius and an exactly similar arrangement in 

 another form like Charadrius hiaticula or in forms like Pluvio- 

 rliynclius ohscurus, jS esocerij x hicinctiis or Charadrius cucullatus 

 (see text-figs. 10 & 11), it seems more reasonable to suppose 

 that such precisely similar structures and physiological adap- 

 tations were iidierited from some common ancestor rather 

 than that tiiey were separately acquired, in each case, as the 

 result of exactly similar functional strains or habits acting 

 independently. If this is so, such characters can, if selected 

 with judgment, surely be regarded as evidence of affinity and 

 utilized for the purpose of chissification ? 



Provisional Classification of the CiiAitADiiiiD^. 



I am inclined, at any rate, to use these characters pro- 

 visionally, along with others, in an attempt to classify the 

 Charadriidai. Working with the somewhat meagre material 

 at present available, there are good reasons which lead one to 

 think that the following genera might be grouped under a 

 heading which I propose to term the Pee-Charadkiin^, that is 

 Piuvialine forms in which the lacrymals are free, and present 

 conspicuous outwardly projecting processes very similar to 

 what is seen in the Laridse, and in which the foramen for 

 the passage of the nasal duct is absent, its place being taken 

 by a groove situated laterad of the anterior extremity of 

 the frontals, an arrangement also characteristic of the 

 Laridie. To this group belong the following : — Leucopolius 

 [ale.randriniis : occidental'is ; ruficapillus ; nianjinalus ; pecu- 

 arias ; sanctw-heleud' ; collai'is ; Jalklandiciis^ : Squatarola : 



