GLOSSARY OF TECHNICAL TERMS. 
Abdomen. Belly. 
Abdominal. Pertaining to the belly, —said of the ventral fins of fishes 
when inserted considerably behind the pectorals, the pelvic bones 
to which the ventral fins are attached having no connection with 
the shoulder girdle. 
Abortive. Remaining or becoming imperfect. 
Acuminate. Tapering gradually to a point. 
Acute. Sharp-pointed. 
Adipose fin. A peculiar, fleshy, fin-like projection behind the dorsal 
fin, on the backs of Salmons, Cat Fishes, etc. 
Adult. A mature animal. 
Aigithognathous. Having the peculiar palate of Passerine birds. 
Air-bladder. A sac filled with air, lying beneath the back-bone. of 
fishes, corresponding to the lungs of the higher vertebrates. 
Allantois. An organ of the embryo. 
Altrices. Birds hatched in an immature condition, reared in the nest 
and fed by the parents. 
Altricial, Having the nature of Altrices. 
Alula. The feathers attached to the “thumb” (rather the “index fin- 
ger ”) of a bird. 
Alveolar surface. A portion of the jaw of a turtle, where the teeth- 
sockets (alveola) are developed in other reptiles. 
Amnion. An organ of the embryo. 
Amphicelian. Double concave, — said of vertebre. 
Anadromous. Running up,—said of marine fishes which run up rivers 
to spawn. 
Anal. Pertaining to the anus or vent. 
Anal fin. The fin on the median line, behind the vent, in fishes. 
Anal plate. The plate, immediately in front of the vent, in serpents, 
often divided in two by a median suture. 
Anchylosed. Grown firmly together. 
Anteorbital plate. The plate (one or two) in front of the eye in ser- 
pents, with its longest diameter vertical; also called preocular. 
Antrorse. Turned forwards. 
Anus. The external opening of the intestines ; the vent. 
