GLOSSARY OF TECHNICAL TERMS CXXVU 



Buccal. Of the mouth. 



Caducous. Falling off. Said of certain plate-like scales on the belly of darters. 

 Gmcum. A blind sac, or tubular diverticulum, connected with the alimentary canal. 

 (Fig. 2, pyl.) 



Canines. Conical teeth (in jaws) which are larger than the rest, as in the pike- 

 perch. 



Cardiform. Said of teeth which are coarse and sharp, like wool-cards. 

 Qarinate. Keeled ; having a sharp median ridge. Said of the belly of certain herring- 

 like fishes. 



Catadromous. Going down to the sea to spawn, as does the common eel. 



Caudal. Pertaining to the tail or caudal fin. 



Caudal peduncle. The fleshy (usually tapering) end of the body, between the anal 



and caudal fins. (Fig. 1, cp.) 

 Centrum. The body of a vertebra. 

 Chiasma. The union of the trunks of the optic nerves, in ganoid fishes. In teleos- 



tean fishes (recent bony forms) the optic nerves cross or interlace without 



uniting to form a solid chiasma. 

 Chin. The space between the two rami of the lower jaw. 

 Chondrocranium. The rudimentary cartilaginous cranial skeleton, corresponding 



to the primitive skull of cartilaginous fishes, of which traces remain in recent 



bony forms. 

 Clavicle. An element of the shoulder girdle. 

 Compressed. Flattened from side to side. 

 Conus arteriosus. A muscular and contractile bulb between the ventricle and the 



root of the aorta. It is furnished interiorly with one or more transverse rows of 



pocket-shaped valves to prevent a backward flowof the blood. (Fig. 2, aob.) 

 Coracoid. (See Hyper- and hypo-coracoid.) 



Ctenoid. With the posterior edge pectinated. Said of the scales in most spiny- 

 rayed fishes. 

 Cycloid. Smooth-edged. Said of the concentrically striated (not ctenoid) scales of 



typical soft-rayed fishes. 

 Dentary. An element of the lower jaw, usually bearing teeth. 

 'Dentate. With tooth-like notches. 

 Depressed. Flattened from above downwards. 



Depth. The vertical diameter or distance through, as of the body or head of fishes. 

 Dorsal. Pertaining to the back. 

 Dorsal fin. The fin on the back, in front of the adipose'fin, if that is present. (Fig. 



1, dl, and d2.) 

 Ectopterygoid. A paired bone of the roof of the mouth. (Fig. 1 and Fig. 56, ecp.) 

 Emarginate. With a slight, shallow notch at the tip. Said of the caudal fin of 



fishes. (Fig. 7.) 

 Entopterygoid. A paired bone of the roof of the mouth, behind the ectopterygoid. 



(Fig. 56, enp.) 

 Falcate. Scythe-shaped. 

 Falciform. (See falcate.) 



Fauna. The assemblage of animals inhabiting a region. 

 Filament. Any slender or thread-like structure. 

 Filamentous. Slender or thread-like; said of certain elongated fin-rays in some 



fishes. 

 Fontanelle. An unossified space in the roof of the skull, filled with cartilage or 



covered with membrane. 

 Foramen. A hole or opening. 

 Frontal. One of the anterior bones of the roof of the skull. 



