Glossary of Technical Terms 



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 border. 



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 sun- 

 fishes. 



Opisthoccelian. 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. 



Ovovivi parous. 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, i on each side extend- 

 ing 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 vertebrae 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, correspond- 

 ing 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. 



Pharyngeal bones. Bones behind the gills and at the beginning of the oesopha- 

 gus of fishes, of various forms, almost always provided with teeth; usually 

 one pair below and two pairs above. They represent a fifth gill-arch. 



Pharyngobranchials. Upper elements of the branchial arches, usually bearing 

 teeth. 



Pharyngognathous . Having the lower pharyngeal bones united. 



Physoclistous. Having the air-bladder closed. 



Physostomous. Having the air-bladder connected by a tube with the alimentary 

 canal. 



Pigment. Colouring matter. 



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