GLOSSARY. 95 



Os clo'acaB (L. bone of the cloaca). A bone which in some 



Lacertilia supports the front wall of the cloaca. 

 Os cox'ee (L. hip-bone). Another name for the innominate bone 



of the pelvis. 

 Os en ceinture (Fr. girdle bone). A peculiar cartilage bone 



found in the skull of the frog. 

 Os innomina'tum (L. nameless bone). The large bone of the 



pelvis in the higher Vertebrata, which is formed by the . 



coalescence of the ischium, ilium, and pubis. 

 Os lin'guae (L. bone of the tongue). Another name for the 



hyoid bone. 

 Os mag'iuim (L. large bone). One of the bones of the carpus, 



also termed capitatum. 

 Os odontoide'um (L. tooth-shaped bone). The peg-like bone 



on which the head rotates, and which may be either a sepa- 

 rate bone, or, as in the higher Vertebrata, may become 



ankylosed with the second vertebra. 

 Os orbi'culare or lenti'culare (L. orbicular or lentil-shaped 



bone). The name formerly given to the tubercule of the 



incus which articulates with the stapes of the tympanum 



of the ear, and which is now regarded as part of the incus. 

 Os pla'num (L. flat bone). Another name for the orbital plate 



of the ethmoid bone. 

 Os pu'bis (L. pubic bone). A bone of the pelvis which forms 



in the higher Vertebrata the anterior and inferior segment 



of each os innominatum. 

 Os tin'cae (L. tench's mouth). The mouth of the uterus by 



which it opens into the vagina. 

 Os u'teri exter'num (L. exterior mouth of the womb). The 



aperture by which the uterus communicates with the vagina. 

 Os u'teri inter'num (L. interior mouth of the womb). A name 



sometimes applied to the constriction between the neck 



and body of the uterus. 



Os'cula (L. little mouths). The exhalent apertures of sponges. 

 Osmd'sis (Gr. othed, I push). The diffusion of fluids through 



membranes. 

 Os'sa suprasterna'lia (L. the bones above the sternum). Two 



small nodules of bone sometimes found in connexion with 



the sternum. 

 Os'sa trique'tra (L. triangular bones). Small pieces of bone 



sometimes found between the cranial bones. 

 Os'sa Wor'mii (L. Wormian bones). Another name for the ossa 



triquctra, also termed ossa suturarum (bones of the sutures). 



