404 FISHES OF NORTH CAROLINA. 



Ganoid. A group of fishes characterized by having body more or less completely covered with 



bony plate-like scales; also said of the peculiar scales of such fishes. 

 Gape. The opening of the mouth. 



Gills. The respiratory organs of fishes, performing the functions of the lungs of higher ani- 

 mals; there are 2 to 4 on each side in ordinary fishes. 

 Gill-arches. The bones supporting the gills and gill-rakers; usually consisting of a short upper 



arm and a long lower arm. 

 Gill-membranes. The membranes covering the branchiostegal rays; the membranes of the 



two sides may be joined together across the isthmus (q. v.) or inserted on the isthmus. 

 Gill-opening. The slit-like aperture leading to the gill-cavity. 

 Gill-rakers. Bony processes of various shapes and sizes attached to the inner margin of the 



gill-arches, used in straining food from the water. 

 Gonads. Sexual glands. 

 Height. Vertical diameter. 

 Hemal. The term applied (1) to the lowermost spine of the caudal vertebrae in fishes; (2) to 



the arch for the passage of a blood vessel at the base of such a spine. 

 Heterocercal. Term applied to the tails of fishes when vertically unequal, the backbone being 



deflected upward, as in the sharks. 

 Homocercal. Term applied to the tails of fishes when equal, the backbone extending to the 



middle of caudal base, as in most of the common fishes. 

 Imbricate. Overlapping; said of scales that overlap like shingles. 

 Incisors. Cutting teeth, usually in front of jaws. 

 Interorbital. Space between the orbits or eyes. 

 Isthmus. The region between the lower part of the gill-openings. 

 Jugular. Pertaining to the throat; said of ventral fins when attached to the throat, in advance 



of the pectorals. 

 Keeled. Ridged; having a ridge or elevation, like the keel of a boat. 

 Lamella. A thin plate or layer. 

 Larva. The immature stage of certain fishes. 

 Lateral. Pertaining to the side. 



Lateral line. A series of tubes or pores along the sides of fishes, secreting mucus and contain- 

 ing organs for the perception of shocks. 

 Lunate. Shaped like a (new) moon; said of a fish's tail with a broadly concave margin. 

 Mandible. The lower jaw. 

 Maxilla, or maxillary. The upper jaw. 



Maxillaries. The outermost and most conspicuous of the bones of the upper jaw. 

 Molar. A grinding tooth. 

 Nape. The back of the neck. 



Neural arch. The arch in a vertebra through which the spinal cord passes. 

 Neural canal The series of neural arches. 

 Neural spine. The uppermost spine of a vertebra; the prolongation of the two bony plates 



which unite to form a neural arch. 

 Nuchal. Pertaining to the nape. 

 Obsolete. Faint; imperfectly developed. 

 Obtuse. Blunt. 



Occipital. Relating to the occiput. 

 Occiput. The back of the head. 



Ocellus (plural ocelli). An eye-like spot; usually a dark spot with a lighter border. 

 Ocellated. Having an ocellus or ocelli. 

 Opercle or operculum. The flat bone on the side of the head which protects the gills; the giU- 



cover. 

 Opercular flap. The ear-like flap of skin projecting from the posterior edge of the opercle, 



especially marked in the sun-fishes. 

 Orbit. The bony cavity in which the eye lies. 

 Orbicular. Nearly circular in outline. 

 Oval. Egg-shaped; said of the outline of a fish. 

 Oviparous. Reproducing by means of eggs which are fertilized and developed outside the 



body. 

 Ovoviviparous. Reproducing by means of eggs which are hatched or partly hatched within 



the body of the parent, as some of the sharks and skates. 

 Ovum (plural ova). Egg. 

 Palatines. Two bones in the roof of the mouth, one on each Bide of the vomer, often provided 



with teeth. 

 Papilla. A small fleshy projection. 

 Papillose. Covered with papillae. 

 Pectinate. Toothed like a comb. 



