374 GLOSSARY OF TECHNICAL TERMS. 
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. 
Web. The vane of a feather, on either side of the rhachis or “stem; ” 
also, the membrane connecting the toes. 
Xiphisternum. Tip of the sternum. 
Zygodactyle. Yoke-toed; having the toes in pairs, — two in front, two 
behind. 
Zygoma. The malar or cheek bone. 
EXPLANATION OF SIGNS AND ABBREVIATIONS. 
I. FisHes. 
L. = Total length in inches of a well-grown example. 
D. = Dorsal fin. 
2d D. = Second dorsal fin. 
£.= Pectoral fins. 
V. = Ventral fins. 
A. = Anal fin. 
C. = Caudal fin. 
B. = Branchiostegals. 
Vert. = Vertebre. The number is usually divided into abdominal and 
caudal vertebre; the latter having the hemapophyses united, 
forming hemal spines. Thus Vert. 10+ 14, the usual number 
in typical fishes, means 10 abdominal and 14 caudal vertebra. 
d = Male. 
2 =Female. 
Roman numerals used with abbreviations for the fins indicate the 
number of spines or inarticulate rays in a fin. Arabic numerals indicate 
the number of soft rays. Ina fin containing both spines and soft rays, 
a comma (,) separating the numerals indicates that the two kinds of 
rays are continuous, or more or less connected. A dash (—) indicates 
