GLOSSARY 483 



Cephalaspis (Gr. kephale, head ; aspis, shield) : an extinct genus of fishes 



belonging to the order Osteostraci of the class Ostracodermi. 

 Cephalic apodeme (Gr. kephale, head ; apo, with ; demas, body or frame) 



the internal skeleton of the head, present in some arthropods and 



molluscs. 

 Cephalopoda (Gr. kephale, head ; pous, foot) : a class of Mollusca which 



includes the cuttle-fishes, squids, octopuses, and nautili. 

 Ceratodus (Gr. keras, horn ; odous, tooth) : a genus of the lung fishes or 



Dipnoi (Australia). 

 Ch/ETOGNATha (Gr. chaite, bristle ; gnathos, jaw) : an order of the phylum 



Nematohelminthes, or Round-worms, comprising the marine arrow 



worms (Sagitta). 

 Chelae, Chelate (Gr. chile, claw) : the prehensile claws which are present 



on some of the limbs of certain Crustacea, e.g. the lobsters and 



crabs. 

 Chelonia (Gr. chelone, a tortoise) : an order of the class Reptilia, comprising 



the tortoise and turtles. 

 Chelydra (Gr. chelus, like a tortoise ; udor, water) : a genus of turtles or 



water tortoises. 

 Chimara (Gr. chimaira, monster) : a primitive type of deep-water fish belong- 

 ing to the order Holocephali. 

 Chitin (Gr. chiton, cuirass) : a nitrogenous horny material, which is deposited 



in the outer epithelial layers of certain invertebrate animals, to form a 



hard, protective covering, as in the exoskeleton of the Crustacea. 

 Chiton (Gr. chiton, coat of mail) : a genus belonging to the class Amphineura 



of the Mollusca. The back is covered by a jointed shield. 

 Chondrichthyes (Gr. chondros, cartilage ; ichthus, fish) : cartilaginous fishes, 



including the sharks and rays. 

 Chondrostei (Gr. chondros, cartilage ; osteon, bone) : an order of Ganoid 



fishes comprising the sturgeons and spoon-bill, characterized by few 



replacing bones. 

 Chromatophore (Gr. chroma, colour ; phoreo, carry) : connective tissue cells 



found in the derma and other mesodermal tissues, which contain large 



pigment granules and are often branched. 

 Cirripedia (L. cirrus, a tuft or crest of curled hair or feathers ; pes, foot) : an 



order of the Ostracoda including the barnacles, in which eyes are afivays 



wanting in the adult fixed-form of the animal. Both median and lateral 



eyes, however, may be present in the Cypris larva, e.g. Lepas fasci- 

 cular is. 

 Cistella (L. cistella, small box) : a Brachiopod in which the upper valve of the 



shell articulates with the lower by a horizontal hinge. It contains a 



shelly-loop for the support of the lophophore. The trochophore larva 



has one or two pairs of ocelli. 

 Cladocera (Gr. klados, branch ; keras, horn) : an order of Crustacea having 



branched antenna;, including Daphnia and Polyphemus. 

 Coccosteus (Gr. kokkos, berry, kernel ; osteon, bone) : a genus of extinct 



fishes belonging to the order Arthrodira. 



