196 



produces a facial appearance distinctly reminiscent of that of a pug dog. 'J'he 

 whole of the muzzle region appears to be thrust back towards the face, so that 

 it becomes pressed beneath an over-growing fold of skin. It would be difficult 

 to find young animals, at the stage of development represented by the completion 

 of hair growth, more unlike the adult than these pug- faced young are to the 

 parent animal with its specialized, elongated muzzle and jaws. No doubt the 

 exacting business of hanging suspended from a nipple without the support 

 afiforded by a pouch plays some part in the production of this curious facial 

 development ; nevertheless, the young of the Bandicoots show the typical 

 elongated snout of the adult during pouch life, despite the absorbing role of 

 nipple grasping. (See No. 3 of this series, Isoodon barrozvcusis, vol. xlvi., 

 1922, fig. 4, p. 42.) The young animal at the conclusion of its dependent life 

 should afiford an interesting study in the readjustment of the cranial skeleton, 

 for a young skull, 14 mm. in total length, shows an ossific facial architecture 

 which is so unlike that of the adult that it is necessary for very remarkable 

 changes to be brought about in a comparatively short interval. Many inter- 

 esting, problems connected with the development of Myrmccohius will, how- 

 ever, probably remain unsolved for lack of material. It is now a very rare 

 animal ; it seems impossible to obtain living specimens, and I know of no records 

 of their having been bred in captivity. 



Fig. 2. 



Myrmccohius fasciatiis. 



Facial vibrissae of a 23 mm. R.V. embryo. 



Hair. — Hair is present on the head of the 23 mm. R.\'. specimen. It is 

 sparse, coarse, and nearly erect. At this stage it is not pigmented, and it is 

 confined to the head and face. The larger embryos ^re completely hair-covered, 

 but the growth of hair is more sparse upon the hinder end of the body and upon 

 the limbs than on the head and face. The hair becomes appreciably shorter 

 when traced caudad. It is all particularly coarse, and. at this stage, it is 

 difficult to distinguish body hairs from true vibrissae. This is especially the 

 case upon the face, where coarse bristle hairs on the eyeliis, and behind and in 

 front of the eye. mask the true vibrissae. which were fully developed at the 

 23 mm. R.V. stage in the absence of the coarse facial nairs. In the larger 

 embryos the hair is pigmented, there being entirely black hairs interspersed with 

 the colourless hairs. These black hairs are present upon the face. head, and 

 shoulders, but are absent on the hinder end of the body. The red hairs typical 



