AMPHIPODA 



367 



1. Orchestia Leaeli. Dark-colored amphipods in which the first 

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

 and the first gnathopod is subclielate 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. 576 — Orchestia agilis (Verrlll). 1, flagellura of second antenna; 2, ped- 

 uncle ; 3, first gnathopod ; 4, second gnathopod ; 5, perlopods ; 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; wiien 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) 

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

 of the second: 2 species. 



Fig. 578 — Talorches- 

 tia longicornis (Paul- 

 meier). A, second 

 gnathopod of male ; B, 

 first gnathopod of fe- 

 male ; C, second gnath- 

 opod of same. 



Small amphipods 



* 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. 



