GLOSSARY. 105 
Os pubis (L. pubic bone).—A bone of the pelvis. In 
the higher Vertebrata a portion of the os 
znnominatume. 
Os trigonum (Gr. triangular bone).—The posterior 
part of the astragalus. Frequently developed 
from a separate centre of ossification. 
Ossa suprasternalia (L. bones of the sternum).— 
Applied to two small nodules of bone some- 
times found in connection with the pre- 
sternum; they are supposed to represent 
median portions of the episternum. 
Ossa triquetra (L. triangular bones).—Small trian- 
cular pieces of bone sometimes present 
between the bones of the skull. 
Ossa wormii (after Wormian, a Danish anatomist).— 
Bones found in sutures such as the ossa 
triquetra, sometimes termed ossa suturarum. 
Osseus (L. os, a bone).—Composed of, or resembling 
bone. 
Ossicules.—Small bones. 
Ossicula auditus (L. little hearing bones).—The three 
small bones in the tympanum of the ear. 
Ossification (L. os, a bone; /aczo, I make).—The 
process by which cartilage or membrane is 
converted into bone. 
Osteoblast (Gr. osteon, a bone ; d/astos, a germ).—The 
bone-cells which probably secrete the osteogen. 
Osteoclast (Gr. osteon, a bone; kao, 1 break).—A term 
applied to the large nucleated cells which 
form excavations in bony tissue during the 
process of absorption. 
