96 GLOSSARY. 



Os'seous (L. os, a bone). Bony. 



OssFcula (L. diminutive of 0s, a bone). Certain small cal- 

 careous bone-like structures in the skeleton of the Echino- 



dermata. 

 Ossi'cula audi'tus (L. little hearing bones). The name of the 



small chain of bones in the tympanum of the ear. 

 Ossification (L. 0s, a bone ; facio, I make). The process by 



which inorganic material is deposited in cartilage or mem- 

 brane, thereby converting them into bone. 

 Os'teoblast (Or. osteon, a bone; blastos, a germ). & term 



applied to the so-called bone corpuscles or bone cells 

 , which probably excrete the osteogen. 

 Os'teoclast (Gr. osteon, a bone ; klao, I break). A term applied 



to the large nucleated cells which excavate pits in bony 



tissue in the process of absorption of bone. 

 Osteoden'tine (Gr. osteon, a bone ; L. dens, dentis, a tooth). A 



hard substance deposited in the inner surface of the dentine 



of teeth. 

 Os'teogen (Gr. osteon, a bone ; gennao, I produce). A term 



applied to the soft tissue which in the formation of bone 



becomes ossified. 

 Osteo'logy (Gr. osteon, a bone ; logos, a discourse). The branch 



of Anatomy which treats specially of the structure and 



arrangement of the bony framework of vertebrated 



animals. 

 Os'tium (L. the door of a house, entrance). Applied to certain 



small openings, as the ostium or opening of the Fallopian 



tube into the uterus. 

 Ostraco'da (Gr. ostrakon, a shell). A group of the Crustacea 



possessing hard shells. 

 Ota'ridae (Gr. ous, dtos, the ear). A group of the Pinnipedia 



comprising the eared seals. 

 O'tic (Gr, ous, dtos, the ear). Relating to the ear. The name 



of one of the cerebral ganglia which lies close to the 



Eustachian tube of the ear. 

 Otoco'nia (Gr. ous, otos, the ear). Small calcareous particles 



found in the fluid of the labyrinth of the ear. 

 O'toliths (Gr. ous, otos, the ear ; lithos, a stone). Frequently 



used in the same sense as otoconia, but more especially 



employed to denote the larger calcareous bodies found in 



the ears of fishes and other animals. 

 Ova'rioles (L. ovum, an egg). The tubes of which the ovaries 



of some Insecta are composed. 



