GLOSSARY OF TECHNICAL TERMS. 
Abdomen. The belly; the cavity containing the digestive and repro- 
ductive organs. 
Adipose fin. A peculiar, fleshy fin without rays but occasionally with a 
spine, occurring on the back behind the dorsal fin of most cat fishes, 
characins, etc. : 
Air-bladder. A sac filled with air, lying beneath the backbone and in 
or behind the abdominal cavity; also known as swim-bladder. 
Anal. Pertaining to the anus or vent. 
Anal fin. The fin on the median line behind the vent. 
Antrorse. Turned forward. 
Anus. The external opening of the intestine; the vent. 
Articulate. Jointed; said of soft fin rays. 
Azygous. Occurring singly; not paired. 
Barbels. An elongate fleshy projection, usually about the head; also 
called whiskers, present in most cat fishes. 
Bicuspid. Having two points. 
Branchie. The gills. 
Branchiostegals. Slender bones forming the support for the branchi- 
ostegal membranes lying under the head and below the opercular 
bones. 
Canines. Long conical teeth. 
Carinate. Keeled; having a single ridge along median line. 
Caudal. Pertaining to the tail. 
Caudal fin. The fin on the tail. 
Caudal peduncle. The region between the anal and caudal fins. 
Coecum. An appendage of the form of a blind sac connected with the 
posterior end of the stomach, or pylorus. 
Compressed. Flattened from side to side. 
Ctenoid. Rough-edged; said of scales when the posterior margin is 
spinous or pectinate. 
Cycloid. Smooth-edged; said of scales when the posterior margin is 
not rough; scales showing concentric lines or striations. 
Deciduous. Falling away or out. 
Decurved. Curved downward. 
Dentary. The principal or anterior bone of the lower jaw or mandible. 
Depressed. Flattened vertically. 
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