1010.] Charart('r>t of Tupaia and Piilocfrcii.s. 271 



Tesics. The Tii})aiid;c .stuiul higher than any other Iiiseetivores in the 

 permanent descent of the testes into a hairv scrotum, as opposed to a tempo- 

 rary descent into a "cremaster sack." But the conditions are more primi- 

 tive than in tyi)ical Placentals: first, because the opposite testes are not 

 appressed to each other but each remains enclosed in its own cremaster sack 

 in the scrotum; secondly, because the testes do not continue their descent 

 beyond the penis but remain anterior to it and thus j)arallel the conditions 

 in Macropus (rf. Weber, 1904, p. 271, fig. 226). 



Uterus. In Tupaia, as in Gipnivura, the median corjjus uteri may be- 

 come so short that the right and left uteri are almost entirely separate 

 (Weber), but they never open separately into the vagina and the conditions 

 are thus much less })rimitive than in Orycteropus and many Rodents. 



Dentition. Tupaia (Fig. 22, B) and Ptiloeereus (Fig. 21) lack only i^ 

 and \)\ of the complete Placental formula. P is subvertical (in Ptiloeereus 

 it is also enlarged) and pointed and its posterior side cooperates with the i)ro- 

 cumbent i^ i^ i'l seizing the food. This condition could apjKxrently give rise 

 to the diprotodont modification observed in the Mixodectidte and certain 

 lemuroids. P (?) in Tupaia is simple, in Ptiloeereus it is a relatively large 

 premolariform tooth with a small posterior basal cusp. It opposes the 

 minute ig and the compressed sub-premolariform lower canine. P a])pears 

 to be represented in Ptiloeereus by a minute alveolus. The upper eauiue in 

 Tupaia is small conic, not recurved. In Ptiloeereus it is like the adjacent 

 premolar (p-) and has two roots. The lower canine in both genera is ([uite 

 small, and works in front of p-, pi apparently being absent. 



Thus with regard to the front teeth Ptiloeereus and Tupaia agree in 

 family characters. The former however approaches the conditions seen in 

 the primitive Zalambdodont Microgale much more closely than does Tupaia; 

 but it seems cjuite possible that these resemblances are homoplastic. 



P|, p| are much more reduced in Ptiloeereus than in Tupaia and in this 

 reduction the former genus i)arallels the Shrew^s, Mijogale and other Insecti- 

 vores with enlarged anterior incisors. P| and m|E| in Tupaia have higher 

 more pointed cusps than in Ptiloeereus, in which omnivorous adaptations 

 are indicated in the more bunodont crown and stouter hypocone; and this 

 fact, taken in connection with the enlarged anterior incisors and stouter 

 malars of Ptiloeereus suggest greater powers of mastication and perhaps a 

 larger proportion of fruits and seeds in the diet. The upper molars of Ptilo- 

 eereus (Fig. 21) have in certain respects departed less from the primitive 

 type exliibited in Ictops than have those of Tupaia: for in Tupaia the para- 

 and metastyles are very prominent and the mesostyle (in correlation with the 

 enlargement of the hypoconid) is very large and exhibits a tendency to 

 divide in two (ef. Galeopitheeus) whereas in Ptiloeereus the mesostyle is 



