GLOSSARY. 133 



BLASTODERM (^AooWs, a sprout ; Sep/, skin), the superficial surface of the embryo 



in its earliest condition. 

 BLASTOIDEA (j3A.a<rr<fo, a sprout ; eTSos, appearance), an extinct order of Echino- 



dermata. 

 BOTHRENCEPHALUS (fitdpos, a pit ; K6(poA^, head), the broad-worm, a genus of 



Tseniada. 

 BBAcmopoDA (Ppaxlw, the arm ; irous, foot), a class of MoUuscoida, formerly called 



Palliobrandiiata from a mistaken theory that their mantle acts as a respiratory 



organ. 

 BBACT (bractea, a thin layer of metal or wood), applied in zoology to part of a 



hydrozoon, from its resemblance to the bract or sheath of flowers. 

 BRAUYPUS (fipaSvs, slow ; irovs, foot), a genus of Edentata, the sloths. 

 BRAXCHIOGASTEROPODA (Ppa.-yx ia -> gills Arist. H. A. viii., ii. 8 ; yaa-r-^p, belly ; 



irovs, foot), a class of gasteropodous inollusks which breathe by gills. 

 BRAXCHIOPODA (ftpdyxia, gi" s ; TOVS, foot), an order of Crustacea in which the feet 



are modified to serve for respiration. It includes the orders PJiyllopoda and 



Cladocera of Milne-Edwards. 

 BRANCHIO-STEGAL rays (Ppdyxut, gills ; oW-yaj, to cover), parts of the hyoid 



apparatus in fish which support the membrane covering the gills. 

 BTSSCS (&v<r(Tos, fine linen), silky threads secreted from the mantle of some 



Mollusks. 



CADUCOUS (cado, fall), formed so as to fall off. 

 C-ECiM (sc. intestinum\ a blind process of the alimentary canal. 

 CALCANEUM, or os calcis (calx, the heel), the bone of the tarsus which forms the 



prominence of the heel or hock. 

 CANINE (dens caninus), the eye-tooth, well developed in dogs and other carnivora, 



defined as that which comes next to the prsemaxillary suture in the upper 



jaw of Mammals and that of the mandible which shuts in front of it. 

 CARINATJS (carina, a keel), an order of Birds which have the sterna raised into a 



median ridge or keel. 



CARNIVORA (caro, flesh ; vorare, to devour), an order of Mammalia. 

 CAKPUS ((capWs, the wrist), the bones between the forearm and the hand, usually 



eight in number in the higher Vertelrata ; the wrist in Man, the " knee " in 



the Horse. 

 CELL (cetta, a . small room), often applied to any small cavity, but properly 



restricted to a microscopic anatomical element, with a nucleus, cell-wall and 



cell-contents, when typically formed. 

 CENTRUM (/ceWpov, a prick, made by one leg of a pair of compasses), a centre? 



applied specially to the " bodies " of vertebrae. 

 CEPHALOPODA (/ce^oXTj, head ; irovs, foot), a class of Mollusks. 

 CEPHALOTHORAX (/ce^oX^, head ; 0a5po|, breast), the united head and thorax of 



Crustacea and Arachnida. 

 CERCAKIFOEM, like the Cercaria (itepKos, tail', an aquatic worm which is one stage 



in the development of a Trematode fluke. 

 CETACEA (KTJTOS, a whale), an order of Mammalia. 

 CELETOGNATHA (X''TT;, hair; yvddos, the jaw), a class of Aunulosa of which the 



genus Sayitta is the only representative. 



CH^TOPHORA (x^m;, hair ; <pepw, bear), an order of Annelida provided with bristlea. 

 CHEIROPTERA (xt>, hand ; vrfp6v, wing), an order of Mammalia. 



f x r )*'h> claw), the modified fourth pair of thoracic limbs in Lobsters and 



their allies, the modified mandibles in Scorpious. 



