370 



l^KOF. W. J. DAKlX OX THE 



embiyology of West Australian Peripatus, unless specimens are 

 kept alive under artificial conditions in the laboratory through 

 the long summer. 



The regions in the hills where Peripatus is found are baked 

 dry in the summer, and the temperature rises frequently to 

 104° F. in the shade in these valleys. The hidden recesses where 

 protection is sought must be somewhat moist, for on several 

 occasions the mere carriage of specimens for a few hours in a 

 cardboard box, with none or insufficient moist earth, has resulted 

 in the death of the animals through drying up. This is all 

 the more noteworthy, since half-a-dozen specimens will live for 

 days in a small glass tube. When suddenly exposed to the light 

 of day the animals remain motionless, but after a few minutes 

 they may move quite actively to get out of the light. Slime is 

 often ejected from the slime glands on touching the specimen 

 with the forceps or the finger. 



EXTERNAL CHARACTERS. 



Colour and Pattern. 



Both the varieties of Feripatuides occur in two rather different 

 colours, brown, and dark olive-green, and the numbers of each 

 are practically equal. Between tliese two shades there are 

 specimens bearing various intermediate tints, and frequently the 

 brown specimens are so marked with dark brown (almost black) 

 that they have quite a variegated appearance. 



Closer investigation with a dissecting binocular microscope 

 brings out the fact that the entire surface of the animal's body is 

 covered with small papili?e. The pigment in the brown specimens 

 is arranged as follows : There is an almost uniform brown back- 

 ground from which arise the papillae above-mentioned. These 

 papillae are either brown (a little darker than the background) or 

 jet black. Some of them, however, have a. pale yellow area round 

 the base. The arrangement of the papillae is responsible for the 

 dark patterns of the skin. 



In a very dark brown specimen the effect is due to the back- 

 ground being much darker, the papillae remain the same, and the 

 pale yellow areas, as round the bases of certain black-tipped papillae, 

 are conspicuous. If the background is still darker — almost 

 black — with a slight tinge of the brown in it, the effect of the 

 black papillae, the pale yellow areas round some of them, and 

 the colour of the background is to produce the very dark olive- 

 green shade of some of the specimens. 



The ventral surface is more free from papillae and the general 

 background is an almost clear white. In the bright brown 

 specimens, between the legs of each pair there are two patches 

 where the background is a pale grey^ — a, patch to either side 

 of the middle line. On each patch there are minute black papillae. 

 Between each successive pair of legs the background is more or 

 less tinged with pale orange brown and there are minute darker 



