** 



v _ 



No. 16. — Exploration of Lake Titicaca by Alexander Agassiz 

 and S. W. Garman. 



IV. Crustacea. By Walter Faxon. 



The crustacean fauna of Lake Titicaca, as indicated by the dredg- 

 ings of Mr. Agassiz, carried on with the assistance of Mr. S. W. Gar- 

 man, in January and February, 1875, is very meagre. Excepting a spe- 

 cies of Cypris, all the specimens collected belong to one amphipodous 

 genus, Allorchestes, which had hitherto afforded but one or two authen- 

 tic fresh-water species, ranging from Maine to Oregon and the Straits 

 of Magellan. Seven new species are described in this paper from Lake 

 Titicaca. Several of them are remarkable among the Orchestidoe for 

 their abnormally developed epimeral and tergal spines. Some are 

 also noteworthy as comparatively deep-water forms of a family com- 

 monly regarded as pre-eminehtly littoral. I believe that no Orches- 

 tidce have heretofore been found at a depth so great as sixty-six 

 fathoms,* unless it be Orchestia (Talitrus) Brasiliensis Dana and Nicea 

 media (Dana), dredged in the harbor of Rio Janeiro (at what depth is 

 not specified) by the Wilkes Exploring Expedition. The marine spe- 

 cies usually inhabit the shore above low-water mark, and the previously 

 described fresh-water species are found in the shallow water of brooks, 

 pools, or edges of lakes. No strictly fresh-water Orchestidce have 

 been reported from the Eastern continent, although a few terrestrial 

 Orchestia; are described as inhabiting moist soil away from the sea. 



* The greatest depth of the lake is 154 fathoms. 



