CLARIS— CLA WS 89 



CLARIS, a Scottisli name for the Bernacle. 



CLAMATOEES, the third Order of Birds according to the 

 arrangement of Andreas Wagner {Arch, filr Naturgesch. 1841, ii. p. 

 93), in which he included all the PiCARi^ of Nitzsch which were 

 not Zygodactyl or Amphibolic. Subsequently Prof. Cabanis 

 {op. cit. 1847, i. pp. 209-256, and ii. pp. 336-345) gave in greater 

 detail the Families, subfamilies, and genera which he believed the 

 " Order " should comprise, and his are the views which have been 

 adopted by most of the systematic "WTiters who have recognized it. 



CLAVICLES (Lat. davicula, the collar-bone). Each clavicle 

 articulates by its dorsal end with a process on the median side of 

 the dorsal end of the coracoid, or with the scapula, or with both ; 

 the ventral ends of the two clavicles generally fuse with each other, 

 forming the FuRCULA, and approach the anterior end of the crest 

 of the sternum. Between them the CEsoPHAGUS and the Trachea 

 pass from the neck into the thoracic cavity (see Skeleton). 



CLAWS or NAILS are the horny sheaths of the terminal 

 phalanges of the toes and fingers, generally curved, and often 

 sharply pointed. They are produced by a thickening of the Mal- 

 pighian layer, which forms the "nailbed" out of which the corneous 

 cells grow. The toes of most birds are protected by claws or flat 

 nails, only in the Ostrich the outer toe has no nail, or hardly 

 any, but the often reduced hallux is frequently unprotected. The 

 inner side of the nail of the third toe is often serrated like a fine 

 comb, as in Cormorants, Herons (including Scopus), Ibis, Dromas, 

 Cursorius, Glareola, also in many Nightjars ; in Podicipes the distal 

 margin of the third nail is serrated. 



Nilsson, Meves, Stejneger, Collett, and Malmgren {cf. Dresser, 

 B. Eur. Vii. p. 189, pi. 485) have described the periodical shedding 

 of the claws in Lagopus, which grow to a consideralile length during 

 winter, the seasonal extension dropping oflf in spring as do the 

 horny fringes on the toes in the Black G-rouse, Capercally, and allied 

 birds. 



Claws on the tips of the fingers are much rarer. Archseopteryx 

 had a well-developed hooklike claw on each of its three fingers. In 

 recent birds such claws are restricted, when occurring at all, to 

 the pollex and index, being sometimes surprisingly well developed, 

 although hardly functional. They occur more or less regularly on 

 the first two fingers in Struthio and Rhea (occasionally as embry- 

 onic traces even on the third finger), also in Anseres and Birds-of- 

 Prey {e.g. Milvus and Cathartes). A pollex claAv alone has been 

 found in various Anseres, in Callus, Birds-of-Prey (especially well 

 developed in the Kestrel), and individually in the Whitethroat 

 and in the Blackbird. ^ An index claw alone occurs in Casuarius, 



^ Such an example of tlie Whitethroat is in Mr. Seebohm's collection, and 



