FISH OF ONTARIO. 115 



Old (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. 



Opisthocoelian. Concave behind only ; said of vertebrae which connect by 

 ball and socket joints. 



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

 poral usually articulates. 



Orbicular. Nearly circular. 



Orbit. Eye socket. 



Oscine. Musical. 



Oscines. A group of singing birds. 



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. 



Ovoviviparous. 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 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. 



Paragnathous. Having the two mandibles about equal in length. 



Parasitic. Living on, or deriving nourishment from some other living 

 thing. Habitually making use of other birds' nests. 



Parapophyses. The lateral projections on some of the abdominal verte- 

 brae to support ribs. 



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

 prefrontal. 



Paratoid. A glandular body behind the ear in Batrachians. 



Parietal. Bone of the side of the head above. 



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

 pterotic and opiosthotic. 



Pectinate. Having teeth like a comb. 



Pectoral. Pertaining to the breast. 



