April, 1908. Lakes Amatitlan and Atitlax — Meek. 203 



is in February, March, and April. The eggs of this species are 

 laid and then attached to the legs and caudal appendages, and 

 are thus carried until the young are of sufficient size to care for 

 themselves. The eggs and young of the Camaron are carried in 

 the same way. To capture these animals when thus loaded with 

 eggs or the young means much destruction to the species. The 

 Cangrejo is much prized for food. Individuals when taken 

 loaded with young should at once be returned to the water. If 

 water animals are to become abundant and useful, the wholesale 

 destruction of the young should be avoided. 



There are many species of fresh water crabs found in tropical 

 waters, inhabiting streams, lakes, ditches and damp woods. 

 Their food, like that of the Camaron, consists of insects and other 

 small animals, and of water plants. Their abundance in Lake 

 Amatitlan will depend largely upon the protection given them 

 during the time they are taking care of their voung. Lakes 

 Amatitlan and Atitlan, common. 



The smaller Crustacea were comparatively more abundant 

 in Lake Atitlan than in Lake Amatitlan. Many hauls were made 

 with the tow net at or near the surface at nearly all hours of the 

 day, and never, except once, were these forms taken in any con- 

 siderable quantity. On February 1 7th, at about 4 .^o p.m., I made 

 a surface towing in Lake Atitlan, near San Lucas, with only 

 average results. A second short haul, made about three-quarters of 

 an hour later resulted in securing about a pint of these small forms. 

 This haul was made just as it began to rain. It was evident to the 

 naked eye that the surface of the water was alive with these 

 small Crustacea. These forms were not observed to be at the 

 surface in such numbers on several other evenings, about this 

 same time, when examinations were made. 



The collections made at both Lakes Amatitlan and Atitlan 

 were studied by Dr. E. A. Birge, Professor of Zoology of the 

 University of Wisconsin, and by his assistant, Professor C. Juday. 

 The following account of the Phyllopoda was prepared by Dr. E. A. 

 Birge. 



Family SididH*. 



Diaphanosoma brachyurum (Li^ven) G. O. Sars. 



A considerable number of females, not distinguishable from 

 the North American representatives of this species, as found 



