12 



The Philippine Journal of Science 



1915 



and Atya that I have observed use the first and second legs as 

 feeding organs, but in the two genera they are used in a different 

 manner, and this difference seems to be correlated to some extent 

 with their difference in habitat. 



Atya molluccensis de Haan, which is the only species of this 

 genus I have collected in the Philippines, is found in abundance 

 in mountain streams several hundred feet above the sea level, 

 but an occasional specimen is sometimes seen in the streams of 

 the lowlands. Individuals of this species and probably of ot"her 

 species of the genus are found clinging to roots, twigs, grass, 

 etc., in their natural habitat, and this tendency is one of their 

 striking characteristics. In aquaria supplied with running 

 water they show the same tendency, and it is almost as marked 

 in still water. They crawl rapidly when taken out of water, 

 but even the same clinging habit is seen when a suitable object 

 presents itself. The animal seems to be uneasy when there is 



Fig. 1. Atya molluccensis de Haan. Left first 

 leg, outer aspect. X 3.5. 



Fig. 2. Atya molluccensis 

 de Haan. Left first leg, 

 outer aspect, showing chela 

 turned backward for ap- 

 plication to the mouth. 

 X3.5. 



nothing to hold on to, but this uneasiness disappears, even when 

 the atya is removed from water, if it is so placed that it can 

 cling to a finger or to anything of similar shape. In general, 

 Atya molluccBTisis lives in rather swiftly moving, shaded streams 

 where it is necessary for it to cling to roots, etc., in order to 

 prevent its being swept away. As a rule it does not seem to 

 spend much of its time crawling on the bottom and probably 

 does not feed in the mud. I have kept this species in an aqua- 

 rium with and without a mud bottom and in both cases with and 

 without running water, for many months. Never have I seen 

 a specimen feeding in the mud or sweeping organisms off of 

 water plants. In still water they either attach themselves to 

 some root or twig or search for a hole or crevice to protect 

 themselves and remain still without feeding. In a running- 

 water aquarium, however, they find the entering point of the 

 water, seek an object to cling to, and arrange their bodies so as 

 to head upstream. When settled in this position, they are un- 

 doubtedly under conditions very similar to those of their natural 



