GLOSSARY 671 



Postglenoid process, a bony ridge behind the glenoid cavity of the squamosal 



to prevent backward dislocation of the jaw. 

 Postorbital process, a bony projection from the frontal or jugal, bounding 



the eye-socket behind. 

 Premazillary, the anterior bone of the upper jaw, carrying the incisor teeth. 

 Primates, Lemurs, Monkeys, Apes and Man ; cohort; and order of placental 



mammals. 

 Proboscidea, Elephants, etc. ; order of hoofed mammals. 

 Process, a distinct prominence or projection of bone for the attachment of 



muscle or ligament. 

 tProglires, an extinct suborder of the Insectivora. 

 Prototheria, most primitive subclass of mammals ; oviparous. 

 Pubis, the postero-inferior element of the hip-bone. 

 Pyramidal, the external bone in the upper row of the carpus. 

 tPyrotheria, an extinct suborder of fToxodontia. 

 Pyrotherium Beds, see Deseado stage. 



Radius, the internal bone of the fore-arm. 



Rodent, see Rodentia. 



Rodentia, Gnawers ; order of placental mammals. 



Rotular groove, a broad, shallow groove on the anterior face of the femur, 



near the lower end, in which the knee-cap glides. 

 Round ligament, the ligament between the head of the femur and a pit in the 



acetabulum of the hip-bone. 



Sacral vertebra, those of the sacrum. 



Sacrum, a bony mass of fused vertebrse, for the support of the hip-bones. 



Sagittal crest, a ridge of bone in the median line of the cranial roof, running 



forward from the occipital crest. 

 Scaphoid, the inner bone in the upper row of the carpus. 

 Scapho-lunar, a compound bone made up of the coalesced scaphoid, lunar 



and central. 

 Scapula, the shoulder-blade. 

 Section, primary division of a suborder. 

 Sectorial, a carnassial or shearing tooth of a flesh-eater. 

 Selenodont, teeth composed of crescent-shaped cusps. 

 Shaft, the body of a long bone, comprising most of its length. 

 Sheridan stage, older Pleistocene of the Great Plains. 

 Shoulder-girdle, the bones to which the fore limb is attached. 

 Simplicidentata, Squirrels, Rats, Porcupines, etc., etc. ; suborder of Rodentia. 

 Sinus, an air-cavity in one of the skull-bones. 

 Sirenia, Sea Cows and Dugong ; order of marine mammals. 

 Species, the unit group in classification, made up of individuals which are 



most closely similar. 



