BEAK 5 



beak has been used by ornithologists for systematic purposes, 

 and whole groups of birds have received their names from 

 this shape, e.g. dentirostres, lamellirostres, &c. The bill, 

 hovi^ever, varies so greatly in admittedly allied birds that its 

 use for classificatory purposes is not great. As a striking 

 instance of this may be mentioned the Limicolae ; we see 

 there the spatulate bill of Euonyrhynchus, like a diminutive 

 spoonbill, the upturned bill of Becurvirostra, the sideways- 

 turned bill of Anarhrynchus, the longer lower mandible of 

 Bhynchops, and the ibis-like bill of Numenius. Gadow has 

 used for classificatory purposes the complex or simple con- 

 dition of the beak. In some birds, e.g. Eatitse, the horny 

 sheath is composed of several pieces ; in others, "the majority, 

 this is not the case. In birds of prey and in parrots there 

 is present a structure which has been termed the cere : this 

 is simply the basal part of the beak, which has remained soft. 

 Its occurrence in those two groups of birds does not appear 

 to be significant of any close affinity. 



The lamellirostres afford another example of how dan- 

 gerous it is to attempt any decision as to affinities from the 

 form of this organ. It has been insisted that one reason for 

 regarding the flamingo as a long-legged duck is the existence 

 of lamellsB along the beak ; but this feature is also met with 

 in the stork, Anastomus, to which group moreover the bird 

 is now more generally believed to be related. The puffin is 

 nearly exceptional ' in the periodical moulting of a portion of 

 the bill ; but the pelican (P. trachyrliynchiis) casts annually 

 an excrescence upon the top of the upper, beak. Sexual 

 dimorphism in the bill is rare, but is exhibited in a marked 

 way in Heteralocha, where the female has a long and down- 

 wardly curved bill, while that of the male is shorter and 

 .straighter.^ 



' Several auks {q.v.) do so, and it has been asserted of the penguins. 

 ^ See in this matter and for variations Ehleks, Zool. Miscell. i. (Gottingen, 

 1894). 



