GLOSSARY 671 



colliculus. One of the divisions of the corpora quadrigemina. 



colloid. Glue-like. 



colon. The large intestine to the rectum. 



columella auris. The ear bone of amphibia and sauropsida. 



commissure. A bundle of nerve fibers which connect right and left halves of central 

 nervous system. 



Concrescence Theory, i. The theory that separate primordia unite in the median 

 plane to form the right and left halves of the embryo. 2. The theory that com- 

 pound teeth are formed by the fusion of simple conical teeth. 



condyle. A rounded articular surface of a bone. 



congenital. E.xisting at or before birth. 



conjunctiva. The delicate membrane which covers the eyeball and lines the eyelid. 



conus arteriosus, i. The conical portion of the right ventricle which joins the pulmo- 

 nary artery. 2. The valvular region of the ventral aorta. 



copulation. Sexual congress. 



coracoid. The posterior of the two ventral elements of the pectoral girdle. 



coriimi. The deeper mesodermal layer of the skin. 



cornea. The translucent anterior portion of the sclera of the eyeball. 



comified. Converted into horny tissue. 



corona radiata. The projection fibers which radiate from the internal capsule to the 

 cerebral cortex. 



coronary. Encircling like a crown. 



coronoid bone. A membrane bone of the lower jaw. 



corpora bigemina (quadrigemina). The midbrain centers of optic reflexes. 



corpora cavernosa penis. The paired masses of erectile tissue of the penis. 



corpus albicans. The fibrous tissue formed after the discharge of the ovum. 



corpus callosum. A group of commissural fibers which connect the two cerebral 

 hemispheres. 



corpus cavemosmn urethrae. The spongy tissue surrounding the urethra. 



corpus luteum. The yellowish tissue formed in the Graafian follicle when an ovum is 

 discharged and fertilized. 



corpus striatum. The basal ganglion of the cerebral hemisphere. 



cortin. The hormone secreted by the adrenal cortex. 



coxal bone. The hip bone. 



cranium. The brain case. 



cretin. A type of idiotic dwarf supposedly caused by deficient thyroxin secretion. 



cribriform plate. A sieve-like portion of the ethmoid bone. 



cricoid. One of the laryngeal cartilages which resembles a seal ring. 



crista. A crest or ridge of sensory hair-cells. 



crura cerebri. The brain peduncles formed by descending fiber tracts from the 

 hemispheres. 



crypt. A pit or follicle. 



cryptorchism. The condition of undescended testicles. 



cuboid. The most lateral distal tarsal bone of the foot. 



cuneiform bones. Three wedge-shaped bones of the distal tarsals. 



cusp. A conical projection of a tooth. 



cutaneous. Pertaining to the skin. 



cuticle. The epidermis or outer layer of the skin. 



cystic duct. The duct from the gall bladder to the common bile duct. 



deciduous placenta. The primitive placenta in which chorion and uterine mucosa are 

 loosely associated. 



