130 



somewhat ill defined in older embryos. The point of out- 

 standing interest is the fusion of interdigital pad 1 with the 

 thenar pad, and the progressive diminution of the striations. 

 Between the 80 mm. and the 105 mm. stages considerable 

 readjustment takes place in the disposition of the sole in the 

 region of the base of the first pedal digit (see (B) and (C) in 

 fig. 13). Professor Collett has described in an embryo "about 

 100 mm., from snout to vent" 2 pads at the base of the big 

 toe, but gives no description of the pads in the adult. This 

 change is presumably to be correlated with the loss of 

 opposibility of digits 1 and 2 to digits 3, 4, and 5 in the 

 manus. It would seem that the animal had somewhat fallen 

 from the arboreal standards of its immediate stock. The 

 diagnosis made from the conditions of the hands and feet is 

 borne out by Professor Collett's account of its habits : "During 

 the day time it hides amongst the colossal boulders, and 

 leaves the rocks only at night, when it ascends the trees in 

 search of food" (P.Z.S., 1897, p. 332). • 



External Genitalia. — The pouch is normal. The opening 

 directed cephelad, and 4 mammary areas are present. 



DESCRIPTION OF PLATE VI. 



Pseudochirops dahli. 



Pouch young photographed against a background of i^-in. squares. 

 Specimen Male B, Perth Museum, 105 mm. 



