GLOSSARY. 27 



Cir'culus veno'sus (L. venous circle). A venous circle 



surrounding the base of the nipple of the mammary 



gland 

 Circumduc[tion (L. circum, around; duco, I lead). The 



rotation of a limb round an imaginary axis, so as to trace 



out a conical surface. 

 Circumcesophage'al (L. drcum, around; Gr. oiso, future of 



phero, I bear; phagein, to eat). Around the gullet, as 



the circumresophageal nerve-commissures found in the 



Crustacea. 

 Circumval'late (L. circunt, around; vallum, a rampart). 



Surrounded by a rampart, as the circumvallate papillae of 



the tongue. 

 Cir'ri (L. cirrus, a lock of hair). Root-like filaments given off 



from the articulations of some Invertebrata. 

 Cirripe'dia (L. cirrus, a lock of hair; pes, pedis, a foot). A 



division of the Crustacea having curled jointed feet. 

 Clas'pers. A pair of organs by the sides of the tail-fin of the 



male Rays, by which the female is grasped in the act of 



copulation. 

 Claus'trum (L. that which shuts off). A grey lamina on the 



outside of the corpora striata of the human brain. 



Cltvfcula ] (L ' cl cula > a little key). The collar-bone. 

 Cleidoxnastoi'deus (Gr. kleis, the clavicle ; and mastoid process). 



One of the extrinsic muscles of the fore-limb. 

 Clitel'lum (L. clitdlcE, a pack-saddle). A region of the body 



of an earthworm which is swollen as compared with the 



other parts. See also Cingulum. 

 Cli'toris (Gr. probably from kleio, I enclose). A small elongated 



part of the female sexual organs in the higher mammals. 

 Clo'aca (L. a sewer). The common chamber which in many 



animals receives the urinary, generative, and intestinal 



secretions. 

 Cly'peus (L. clipeus, or clypeus, a shield). The broad flattened 



region of the head in a cockroach. 

 Cne'mial crest (Gr. kneme, leg, shin-bone). A protuberance of 



the proximal end of the tibia, which is well marked in all 



walking and swimming birds. 

 Cni'dae (Gr. knide, a nettle). The stinging thread-cells of the 



Coslenterata. 

 Coagnla'tion (L. coagulum, a clot). The process of clotting, 



which some fluids such as blood and lymph undergo. 



