FISH OF ONTARIO. 121 



Trenchant. Compressed to a sharp edge. 



Truncate. Abrupt, as if cut squarely off. 



Tubercle. A small excrescence, like a pimple. 



Tympanum. Drum of the ear; external in some Batrachia, etc. 



Type (of a genus). The species upon which was based the genus to which 

 it belongs. 



Type (of a species). The particular specimen upon which the original 

 specific description was based. 



Type (locality). The particular place or locality at which the type speci- 

 men was collected. 



Typical. Of a structure the most usual in a given group. 



U. 



Ulna. The inner or posterior bone of the forearm. 



Ultimate. Last or farthest. 



Unguiculate. Provided with claws. 



Ungulate. Provided with hoofs. 



Unicolour. Of a single colour. 



Urosteges. The plates underneath the tail of a serpent. 



V. 



Vent. The external opening of the alimentary canal. 



Ventral. Pertaining to the abdomen. 



Ventral fins. The paired fins behind or below the pectoral fins in fishes 



corresponding to the posterior limbs in the higher vertebrates. 

 Ventral plates. In serpents, the row of plates along the belly between 



throat and vent. 



Ventricle. One of the thick-walled chambers of the heart. 

 Versatile. Capable of being turned either way. 

 Vertebra. One of the bones of the spinal column. 

 Vertical. Up and down. 

 Vertical fins. The fins on the median line of the body; the dorsal, anal 



and caudal fins. 



Vertical plate. Central plate on the head of a serpent. 

 Villiform. Said of the teeth of fishes when slender and crowded into 



velvety bands. 

 Viscous. Slimy. 



Viviparous. Bringing forth living young. 

 Vomer. In fishes, the front part of the roof of the mouth ; a bone lying 



immediately behind the premaxillaries. 

 13 F. 



