140 



granular. There are four typical interdigital pads. The thenar pad is present 

 but small. The hypothenar pad is very well developed. A well-marked granule 

 is differentiated in the centre of each pad. 



P^^.— The digital formula is 3 > 4 > 5 > 2 > 1 ; or 3 = 4 > 5 > 2 > 1. In the 

 adult the typical formulais 4 > 3 >5 > 2 > 1. Apical pads are not obvious 

 on the fusiform digits. Three typical interdigital pads are present at 

 the bases of digits 2-3, 3-4, 4-5. In addition there is a small first 

 interdigital pad at the base of the first digit. This pad is absent in the adult, at 

 which stage the first digit is itself far more reduced than it is in the 25 mm. 

 young. It should be noted, however, that the degree of adult development 

 of the first digit is extremely variable. The sole is entirely granular. A well- 

 marked granule is present in the centre of each pad, but no sculpturing is as yet 

 visible on the central granule. 



»L »V 





^M'i-;^-""^' 



Fig. 6. 



- Dasyccrctis cristtcauda. 

 Left manus and pes of a 25 mm. R.V. embryo. 



External goi Italia. — The male genital tubercle is exposed beyond the cloacal 

 margin at the 25 mm. stage. 



The mammary area of the female is of particular interest. Of the three 

 females of the 25 mm. stage, one shows two bilateral mammary primordia, the 

 second shows the two bilateral primordia and a single median more caudad 

 primordium, and in the third (illustrated at fig. 7) there is a suggestion of a 

 median division of the posterior median primordium. Very faint elevations run 

 upon the lateral aspects of these mammary primordia and tend to delimit the 

 mammary area from the general skin surface of the lower portion of the abdomen. 

 Later stages should reveal changes of considerable interest. In the adult there 

 are from 6 to 8 nipples arranged in crescentic lines. Considerable irregularity 



