216 ILLINOIS NATURAL HISTORY SURVEY MANUAL 4 



left of each diagonal line is indicated the number of a certain 

 kind of tooth in each half of the upper jaw, to the right the num- 

 ber of the same kind of tooth in each half of the lower jaw. The 

 total number of teeth in each half of the upper jaw is 10, in 

 each half of the lower jaw 11. Therefore, there are 20 upper 

 teeth and 22 lower teeth and 42 teeth altogether. In each half 

 of the upper jaw in this example there are three incisors (I), 

 one canine (C), four premolars (Pm), and two molars (M). 



dentary bone. One of a pair of membranous bones of the distal 

 (farthest from hinge) part of the lower jaw. 



diastema. A distinct space or gap between two teeth, as shown in 

 fig. +0/. 



digitigrade. Walking primarily on the toes, as in horses and dogs. 



dorsal. Pertaining to the back or upper parts; opposed to ventral. 



dorsoventrally. Between the dorsal (upper) and ventral (lower) 

 sides of an animal. For example, a body or part flattened dorso- 

 ventrally would be unusually broad for its depth, i.e., vertically 

 compressed as opposed to laterally compressed. 



enamel loop. Loop formed by convolutions of enamel of tooth as 

 seen on the grinding surface, fig. l\a-e. 



enamel triangle. Triangle formed by convolutions of enamel of 

 tooth as seen on the grinding surface, fig. l'\b, d, e. 



fenestrated. Having numerous openings, as in skull of a cotton- 

 tail, fig. 40ii. 



flange. A rim or rimlike extension. 



foramen. An opening, as found in the skull, through which nerves 

 or blood vessels pass, fig. 119. 



foramen magnum. Large opening in skull at posterior (rear) end, 

 fig. 117. 



forb. Any herbaceous plant other than a grass. 



frontal or frontal bone. One of a pair of bones forming the roof 

 of the braincase, figs. 117, 118. 



fulvous. A dull yellowish gray or brownish color. 



gestation period. The period of carrying of young normally in the 

 uterus, from conception to delivery; period of pregnancy. 



guard hairs. Long hairs of the pelt that protect the shorter and 

 finer textured fur. 



habitat. The natural abode in which a species of plant or animal 

 grows or lives. 



hard palate. Portion of palate, fig. 119, supported by bone; that 

 part of palate covering the palatal bone. 



herbivore. A mammal that feeds on plant material. 



herbivorous. Plant eating. 



hibernate. To pass the winter in close quarters in a torpid or in- 

 active state. 



incisive foramen. One of a pair of openings in the anterior palate, 

 sometimes called anterior palatine foramen, figs. lZd{f), 119. 



incisor. One of the front teeth between the canines; found in the 

 premaxillary or dentary bones, figs. 118, 119. 



inferior. Lower, as opposed to superior or upper. 



