162 ZOOLOGY. 



v Cirri (Lat. cirrus, a curl of hair) A term applied to the feet of 

 barnacles and acorn-shells, from their resemblance to ten- 

 drils. The filaments attached to the arms of the Brachio- 

 poda. 



Cirripedia (Lat. cirrus, a curl; pes, a foot) A division of Crus- 

 tacea, including the barnacles and acorn-shells. They are so 

 called on account of their curled feet. 



Clavicle (Lat. clavicula, a little key) The collar-bone of the Ver- 

 tebrata. 



Cloaca (Lat. a sewer) The cavity into which the intestine, uri- 

 nary, and genital organs open in birds, reptiles, and one 

 order of mammals (Monotremata). An analogous cavity is 

 found in some invertebrate animals. 



Cocoon (Fr. cocon) The covering of an insect in the pupa state, 

 sometimes consisting of silky hairs. 



Ccelenterata (Gr. koilos, hollow; enteron, an intestine) The sub- 

 kingdom which includes the Hydrozoa and Actinozoa. They 

 are distinguished from the Protozoa, mainly, in having a 

 hollow digestive cavity. 



Ccenosarc (Gr. Jcoinos, common; sarx, flesh) The common con- 

 necting stem in the compound Hydrozoa. 



Commissures (Lat. committo, I join together) The nerve filaments 

 which unite the ganglia or nerve-centres. 



Conchifera (Lat. concha, a shell; fero, I bear) A name sometimes 



applied to the Lamellibrancldata. 



VCondyle (Gr. Jcondulos, a knuckle) The articulating surface of a 

 bone, especially applied to the articulating surface or sur- 

 faces of the occipital bone, which join the skull to the atlas, 

 or first joint of the vertebral column. 



Coracoid (Gr. korax, a crow) A second clavicle found in birds, 

 reptiles, and Monotremata. In man, the "coracoid process" 

 of the scapula resembles the beak of a crow. 



Corallum (Lat. for coral) The calcareous structure secreted by 

 the tissues of the Actinozoa, generally called " coral." 



Coriaceous (Lat. corium, a hide) Resembling leather. 

 : Corpus Call osum (Lat. "firm body") The band of nerve-fibres 

 which unites the two hemispheres of the cerebrum in Mam- 

 malia. 



Corpuscles (Lat. corpusculum, a little body) The rounded solid 

 particles found floating in blood. In most mammals they 

 have the form of " biconcave discs." 



Cortical Layer (Lat. cortex, bark) In the Infusoria this term is 

 applied to the middle layer of the body. It lines the cuticle, 

 and surrounds the central mass of sarcode. 

 l^Cranium (Gr. kranion, the skull) The bony or cartilaginous case 



which surrounds the brain. 

 \X/rop An expansion of the oesophagus found in birds,. 



