137 



It is a very remarkable thing to see the female animal stumbling about 

 with the seven large young clinging to the nipples. They make a load which 

 one would have thought her incapable of supporting, and yet the wonderfully 

 active creature will chase insects and kill mice regardless of her burden. It 

 might also seem that the naked and unprotected young would be perpetually 

 liable to injury since their backs depend to the ground, and they are dragged 

 about here and there as the mother's activities dictate. How long they remain 

 adhering to the nipples is, so far, unknown ; but it is hoped that the point may 

 be cleared up, since this beautiful little animal is easy to keep in captivity. The 

 young are robustly built, large-headed little creatures, with the face remarkably 

 short and the upper jaw somewhat retracted. 



Hair. — The hair upon the head is well developed and already pigmented 

 when the embryo is no longer than 15 mm. in R.V. length. Hair is not discern- 

 able upon the rest of the body at this stage; and it is rather remarkable that 

 no sensory papillae or vibrissae are recognizable at this stage. In the 25 mm. 

 R.V. embryos the hair is beginning to appear all over the body, but it is still 



Fig. 2. 



Dasycercus cristicauda. 

 Facial vibrissae of an embryo, 25 mm. R.V. length. 



much more conspicuous and more deeply pigmented upon the head. All papillae 

 and vibrissae are now well developed. 



Hair tracts. — The arrangement of the hair upon the whole of the head, 

 body, and limbs is of basal simplicity. The face, head, and the whole of the 

 trunk and tail are clothed with hair having a uniform caudad trend. Upon the 

 limbs the hair is uniformly in a distal and post-axial direction. There are no 

 reversals, partings, convergences, or vortices anywhere. (See fig. 1.) 



Vibrissae and papillae. — Although not distinguishable at the 15 mm. stage, 

 all papillae and vibrissae are well developed in the 25 mm. embryos. 



Facial vibrissae. — The vibrissae and papillae are well developed upon the 

 face, but the submental group appears to be entirely lacking. In the adult 

 there are some partially differentiated pale bristles in the submental region ; 

 but these are not recognizable at this stage. The supraorbital papilla is well 

 marked, situated almost at the mid point of the upper eyelid, and giving rise to 

 a couple of dark vibrissae. The mystacial set is clearly divided into an upper 



