532 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 49. 



Through the indulgence of the chief of the expedition the writer 

 was able to devote his whole time to the collection and study of 

 crustaceans, and, as a thorough search was made in each locality 

 visited, the list of species is believed to be representative. My thanks 

 are due to Dr. A. G. Ruthven, who led the expedition, and to Mr. F. 

 M. Gaige, who completed the party. Both were constantly on the 

 alert for crustaceans and helped very materially in securing speci- 

 mens and notes. My thanks are also due to Miss Mary J. Rathbun, 

 who read the manuscript of this paper, gave many valuable sugges- 

 tions, and furnished photographs for the figures of the crabs appearing 

 in this paper. 



CRUSTACEAN HABITATS. 



The crustaceans of Colombia live in a variety of habitats. The 

 aquatic representatives may dwell m the cool swift torrents on the 

 tops of mountains, in the sluggish meandering streams of the low- 

 lands, or among the luxuriant vegetation in the swamps. Terrestrial 

 crustaceans may live in bromeliads, in the rough bark of trees, among 

 fallen leaves, under logs, in rotting tree trunks, in the ground or on 

 its surface. Some crabs and isopods are amphibious, wandering from 

 land to water and back agam as suits their convenience. The habi- 

 tats in the vicinity of Santa Marta may be grouped under the fol- 

 lowing headings: Ocean, mangrove swamps, streams, forest, desert. 



No attempt is made in this paper to consider the marine Crustacea, 

 but it is impossible to study those of land or fresh water without dis- 

 cussing many marine crabs, such as the Gecarcinidae, Ocypodidae, 

 Grapsidae, and Coenobitidae, which wander about on the banks of 

 estuaries (Uca, Gecarcinus), climb among the mangroves (Sesarma), 

 or migrate far inland along the banks of rivers (Cardisoma) . 



The mangrove swamps along the Cienaga Grande swarmed with 

 fiddler crabs (Uca mordax and Z7, minax), which live in holes in the 

 mud among the thickly crowded aerial roots. Sesarmas (S. roherti) 

 climbed about over the mangroves, dodging beneath roots or into 

 their holes when disturbed. These mangrove crabs have a habitat 

 which furnishes them an abundance of food, but they often fall a 

 prey to the herons and raccoons, which are extremely common. 



The streams near Santa Marta are of two sorts: (1) Swift mountain 

 torrents flowing over solid rock or bowlders, and (2) the slow-flowing 

 rivers of the flat country along the coast. The rapid-flowing moun- 

 tain streams contain no proper crustacean fauna, though the amphibi- 

 ous crabs, Pseudothelphusa, and isopod, PMloscia nitida, are often 

 found there. Both these crustaceans are also of frequent occm-rence 

 on land at considerable distances from water. As soon as the streams 

 lose the impetus of their descent from the mountains, however, they 

 are invaded by a horde of slu-imps and prawns. The favorite resort 

 of the strange Atya scahra is among the collections of leaves and other 



