No. 26.] ARTHROSTRACA OF CONNECTICUT. 35 



The following species are found on piles among Hydrolds, 

 sponges, etc. : 



Allorchestes littoralis Grubia compta 



Caprellidas Melita nitida 



Corophium cylindricum Microdeutopus gryllotalpa 



Elasmopus levis Stenot-hoe cypris 



Gammarus locusta S. minuta 



On sandy shores the more common species are the following : 



Allorchestes littoralis T. megalophthalma 



Orchestia agilis Haustorius arenarius 



Talorchestia longicornis Unciola irrorata 



The more common species that are found on rocky shores 

 between high- and low-water marks, and often in the greatest 

 abundance, are the following : 



Orchestia agilis Elasmopus levis 



O. palustris Gammarus marinus 



Gaminarus locusta Unciola irrorata 

 Amphithoe rubricata 



O. agilis is especially abundant beneath masses of decaying 

 sea weed. Gammarus locusta is more common under stones and 

 among rockweed at low-water mark. Amphithoe rubricata 

 abounds in similar situations but apparently prefers Ulva to 

 rock weed. Unciola irrorata is found only at low-water mark. 



MOVEMENTS. 



In general the Amphipoda are very agile and energetic except 

 those species which inhabit tubes, usually of their own construc- 

 tion, or lie buried in the sand or in excavations of wood, like 

 Chelura. 



The most constant and uniform movement is that of the 

 pleopods, by which a current of water is constantly passed 

 forward over the gills. Besides these movements ijt has been 

 observed in some species that the mouth parts move more or less 

 regularly as if the animal were eating although there may be 

 no food whatever in the water. In eating, the mouth parts of 

 Orchestia agilis vibrate about 120 times a minute. 



