CHEIROMYS. 435 



crown : the second premolar, like the three true molars, has a broad, 

 oblong quinque-cuspid crown, four cusps being in two transverse pairs, 

 and the fifth at the anterior and internal angle of the tooth. 



In the broad pectinated incisors of the Galeopithecus the 

 pulp-cavity divides at the base of the crown into as many canals as 

 there are divisions of the crown, one being continued up the centre of 

 each to within a short distance of its apical extremity. The calci- 

 gerous tubes which radiate from these canals have a diameter at 

 their origin of i5;ij5th of an inch : they quickly divide and subdivide 

 dichotomously with rather large and irregular secondary undula- 

 tions, sending off many fine branches and resolving themselves 

 into numerous smaller ramifications which interlace irregularly 

 near the enamel. The tubuli in the body of the tooth have 

 longer trunks, but present a very similar character : the section 

 figured in PI. 115, being taken a little on one side of the central 

 pulp-cavity shows the diverging tubuli cut almost transversely 

 across in the middle of the body of the tooth, and the longi- 

 tudinal course of the wavy ramifying tubes at the margins of 

 the section. The medullary canal or branch of the pulp-cavity 

 is shown in some of the divisions of the crown, at m. Each 

 division of the crown has its proper investment of enamel, which 

 substance is continued for a short distance upon the common base. 



The deciduous teeth appear not to cut the gum before 

 birth, as they do in the true Bats. In a foetus of Galeopithecus 

 Temminckii^ with a head one inch and a half in length, I found 

 the calcification of the first incisor just commenced in the 

 closed alveolus ; the second incisor and the rest of the deci- 

 duous series being represented by the vascular uncalcified matrices. 

 The upper milk teeth (PI. 114, fig. 1&) consist of two incisors, 

 a canine, and two molars ; which latter are displaced and suc- 

 ceeded by the two premolars. The deciduous teeth are six in 

 number in the lower jaw ; the incisors being pectinated, but 

 much smaller than their successors. The true molars are de- 

 veloped and in place before the deciduous teeth are shed. 



168. Cheiromys. — In this genus of Lemurine animals, as in 

 Desmodus amongst the Bats, and Sorex amongst the Insectivores, 



F F 2 



