AMPHIPODA 



367 



1. OECHESTIA Leach. Dark-colored amphipods in which the first 

 antennae are shorter than the basal portion (peduncle) of the second, 

 and the first gnathopod is subchelate in both sexes: 25 species. 



0. agilis S. I. Smith (Fig. 576). First antennae not reaching the 

 tip of the penultimate joint of peduncle of second antenna; length 14 



Fig. 576 



Fig. 577 



Fig. 576 Orchestia agilis (Verrill). 1, flagellum of second antenna; 2, ped- 

 uncle ; 3, first gnathopod ; 4, second gnathopod ; 5, periopods ; 6, jumping legs ; 

 7, abdomen; 8, thorax. Fig. 577 Orchestia palustris (Paulmeier). Explanations 

 as in Fig. 576. 



mm.; color brownish: Atlantic coast, under masses of decaying sea- 

 weed on the shore, as far south as Florida; when disturbed it hops and 

 runs with great rapidity; Europe. 



0. palustris* S. I. Smith (Fig. 577). First antennae reaching 

 beyond tip of penultimate joint of peduncle of the second antennae; 

 length 18 mm. ; color brownish : Cape Cod to New Jersey ; on the shore of 

 salt marshes; Europe. 



2. TALORCHESTIA Dana. Whitish, large am- 

 phipods in which the first antennae are shorter than 

 the basal portion (peduncle) of the second and the 

 first gnathopods are subchelate in the male and not 

 in the female: 20 species. 



T. longicornisf (Say) (Fig. 578). Eyes large; 

 second gnathopods of male very large ; first antennae 

 just reaching to the tip of the penultimate joint of 

 the second antennae; length 25 mm.; color whitish, 

 but sometimes brown: Cape Cod to New Jersey, 

 common on sand beaches, burrowing in the sand 

 in the daytime. 



3. HYALELLA S. I. Smith (Allorchestes Dana). Small amphipods 

 in which the first antennae are longer than the basal portion (peduncle) 

 of the second: 2 species. 



* See "The Salt-Marsh Amphipod, Orchestia palustris," by M. E. Smallwood, 

 Cold Spring Harbor Monographs, III, 1905. 



t See "The Beach Flea ; Talorchestia longicornis," by M. E. Smallwood, Cold 

 Spring Harbor Monographs, I, 1903. 



Fig. 578 Talorches- 

 tia longicornis (Paul- 

 meier). A, second 

 gnathopod of male ; B, 

 first gnathopod of fe- 

 male ; C, second gnath- 

 opod of same. 



