Jordan and Evermann. Fishes of North America. 2893 



Neural canal. The neural arches as a whole. 



Neural processes. Two plates rising vertically, 1 on each side of the 

 centrum of the vertebra, which unite toward their ends and form a 

 spine. 



Neural spine. The uppermost spine of a vertebra. 



Nictitating membrane. The third or inner eyelid of birds, sharks, etc. 



Notochord. A cellular chord which in the 'embryo precedes the vertebral 

 column. 



Nuchal. Pertaining to the nape or nucha. 



Obsolete. Faintly marked; scarcely evident. 



Obtuse. Blunt. 



Occipital. Pertaining to the occiput. 



Occipital condyle. That part of the occipital bone modified to articulate 

 with the atlas. 



Occiput. Back of the head. 



Ocellate. With eye-like spots, generally roundish and with a lighter bor- 

 der. 



Oid (suffix). Like; as Percoid, perch-like. 



Opercle, or operculum. Gill cover ; the posterior membrane bone of the side 

 of the head, in fishes. 



Opercular bones. Membrane bones of the side of the head, in fishes. 



Opercular flap. Prolongation of the upper posterior angle of the opercle, 

 in sunfishes. 



Opisthoc(jelian. Concave behind only ; said of vertebrae which connect by 

 ball-and-socket joints. 



Opisthotic. A bone of the skull to which the lower limb of the post- 

 temporal usually articulates. 



Orbicular. Nearly circular. 



Orbit. Eye socket. 



Osseous. Bony. 



Ossicula auditus. Bones of the ear, in fishes. 



Osteology. Study of bones. 



Oviparous. Producing eggs which are developed after exclusion from the 

 body, as in all birds and most fishes. 



Ovoviriparous. Producing eggs which are hatched before exclusion, as in 

 the dogfish and garter snake. 



Ovum. Egg. 



Palate. The roof of the mouth. 



Palatines. Membrane bones of the roof of the mouth, 1 on each side 

 extending outward and backward from the vomer. 



Palustrine. Living in swamps. 



Papilla. A small fleshy projection. 



Papillose. Covered with papillae. 



Parapophyses. The lateral projections on some of the abdominal vertebras 

 to support ribs. 



Parasphenoid. Bone of roof of mouth behind the vomer. Synonym of pre- 

 frontal. 



Parietal. Bone of the side of head above. 



Parotic process. A posterior lateral process of the skull formed by the 

 pterotic and opisthotic. 



Pectinate. Having teeth like a comb. 



Pectoral. Pertaining to the breast. 



Pectoral fins. The anterior or uppermost of the paired fins, in fishes, cor- 

 responding to the anterior limbs of the higher vertebrates. 



Pelagic. Living on or in the high seas. 



Pelvic girdle. The bones supporting the ventral fins or pelvics. 



Pelvis. The bones to which the, hinder limbs (ventral fins in fishes) are 

 attached. 



Perforate. Pierced through. 



Peritoneum. The membrane lining the abdominal cavity. 



