96 GLOSSARY. 
foot)—A process developed in most birds 
from the region of the tarsal and metatarsal 
bones. 
Hypural (Gr. Zufo, under ; oura, the tail)—The bones 
which in fishes support the caudal fin-rays. 
Iliac (L. z/za, the flanks)—Relating to the region of 
the ilium. 
Tlium (L. z/za, the flanks)—A bone of the pelvic 
girdle; in the higher Vertebrata the ilium 
forms the upper division of the os innomi- 
natum. 
Incisor (L. zzczdo, I cut into)—A cutting tooth. 
Incisura of acetabulum (L. zzczsura, a notch)—An 
incomplete portion of the margin of the 
acetabulum. 
Incisura ethmoidalis.— A notch separating the 
orbital plates of the frontal bone. 
Incisura semilunaris.—The centre or middle notch 
in the upper border of the sternum. 
Incus (L. an anvil)—A small ossicle of the ear. 
Index (L. zzdzco, I point out)—The index or fore- 
finger, the second digit of the manus. 
Infra-orbital (L. 27/ra, beneath).—One or more bones 
beneath the orbit in fishes. 
Infra-temporal crest.—A ridge bounding the tem- 
poral fossa inferiorly and separating it from 
the pterygoid fossa. Synonymous with 
pterygoid ridge. 
Innominate (L. zz, not ; omen, a name).—The bone 
forming the pelvis of higher Vertebrata. 
