KUKENTHAL: ASTYLOSTERNUS ROBUSTUS. 373 
of the same size with very short appendages. I find no males without 
these villosities, for even the smallest male at my disposal possesses 
them. 
It is to be regretted that the collector of these specimens, Mr. 
Schwab, has not given any notes about the time of year when he cap- 
tured the different specimens; but, notwithstanding this, we can draw 
with almost absolute certainty the conclusion that these appendages 
are much more highly developed at one time of year than at other 
times. Moreover it is very probable that this time corresponds with 
the breeding period. Direct observations, of course, would quickly 
settle this question. 
The fact that a younger (smaller) male, contained in the same jar 
with the two adult males possessing fully developed appendages — and 
therefore apparently captured at the same time with these — showed 
this hairy coat in its beginnings, points to the conclusion that the 
appendages are fully developed only on adult animals, and probably, 
as I have already suggested, at the time of mating. 
Now arises the question, from what do these organs originate? 
The reply requires a careful investigation of the female (Plate 5). 
It is quite surprising, that none of the former investigators has ob- 
served the fact, that the females have, on exactly the same parts of 
the body that on the males bear these appendages, small but quite 
distinct tubercles, which have the same diameter as the bases of the 
appendages in the male. Their distribution over exactly the same 
areas of the surface shows clearly that they are homologous with the 
appendages of the males. 
Moreover, if we carefully study the surface of the skin (Plates 1, 3-5), 
we find that both males and females show similar tubercles scattered 
over the whole back, and that they are more closely crowded in the 
region of the angle of the jaws (Plate 3). In some areas of the surface 
of males we may even observe the transition of these tubercles into 
the villous appendages. From these comparisons we must therefore 
draw the conclusion that these appendages have originated from 
tubercles of the skin, such as we find scattered over the skin of this 
species in other regions of the body and such as are recorded from other 
species of Ranidae. . 
These hair-like appendages are therefore to be considered as highly 
developed tubercles of the skin. 
I have studied the microscopical structure of these appendages in 
series of sections, which Mr. S. Kornhauser has been kind enough to 
prepare. The stains which were used were: borax-carmine and bleu de 
