.OSSARY OF TECHNICAL TERMS. 369 



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

 Opercular flap. Prolongation of the upper posterior angle of the oper- 



cle, in Sun-fishes. 

 Opisthocalian. Concave behind only ; said of vertebrae which connect 



by ball and socket joints. 

 Orbicular. Nearly circular. 

 Orbit. Eye socket. 

 Oscirte. M usical. 

 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. 

 Ovoviviparous. Producing eggs which are hatched before exclusion, as 



in the Dog-fish and Garter Snake. 

 Ovum. Egg. 



Palate. The roof of the mouth. 

 Palatines. Membrane bones of the roof of mouth ; one on each side 



extending outward and backward from the vomer. 

 Palmate. Web-footed ; having the anterior toes full-webbed. 

 Palustrine. Living in swamps. 

 Papilla. A small, fleshy projection. 

 Papillose. Covered with papillae. 



Paragituthous. Having the two mandibles about equal in length. 

 Paraspkenoid. Bone of roof of mouth behind the vomer. 

 Paratoid. A glandular body beiiind the ear, in Batrachians. 

 Parietal. Bone of the side of head above. 

 Pectinate. Having teeth like a comb. 

 Pectoral. Pertaining to the breast. 

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



corresponding to the anterior limbs of the higher Vertebrates. 

 Pelage. The iiair of a Mammal, taken collectively. 

 Pelagic. Living on or in the high seas. 

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



are attached. 

 Perforate. Pierced through ; said of nostrils when without a septum. 

 Perissodactylous. Odd-toed (toes 1, 3, or 5). 

 Peritoneum. The membrane lining tlie abdominal cavity. 

 Phalanges. Bones of the fingers and toes. 

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



oesophagus of fishes, of various forms, almost always provided 



with teeth ; usually one pair below and four pairs above. They 



represent a fifth gill-arch. 

 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. Coloring matter. 

 Pineal body. A small ganglion in the brain ; a rudiment of an optic 



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