AMPHIPODA OF SOUTHERN NEW ENGLAND. 



471 



For details concerning the phototactic reactions of this and other species of amphipods, reference may 

 be made to my paper on Phototaxisin the Amphipoda (American Journal of Physiology, vol.5, p. 211 |. 

 This is undoubtedly the species referred to as Orchestia gryllus ( Bosc), by Stimpson, and possibly 

 also by l>e Kay and Say. Bosc's original description, however, does not enable one to decide whether 

 he had specimens of this or some other species of Orchestia. His description and figure apply topalus- 

 tris Smith, as well as to the above, although his statements that grytlus "se trouveen grande quantity," 

 and that "elle saute par le moyen de sa queue et glisse sur la sable, par le meme moyen, avec une 

 rapidite dont on ne se fait pas une idee," would more naturally be made concerning agilis than paluslris. 



Orchestia palustris Smith. 



First antennae reaching a little beyond tip of penultimate basal joint of second antenna', the three 

 basal joints of subequal length; flagellum nearly or quite as long as peduncle; second antennae with 

 penultimate basal joint two-thirds as long as the last one; flagellum longer than peduncle; second, 

 third, and fourth epimera quadrate, rather broader than deep; first gnathopods of male much as 

 in agilis, the carpus having a prominent rounded inferior lobe and the propodus distally widened and 



Orchestia palustris. Woods Hole. First antenna and third uropod drawn to a larger scale than the other parts. 



produced into a rounded lobe, at the infero-posterior angle; second gnathopods of male with hand 

 oval, palm very oblique and evenly convex and spinous, the posterior end defined by a small prom- 

 inence within which the tip of the dactyl closes; otherwise the palm forms an even curve with the 

 posterior margin of the hand; dactyl fitting closely to the palm. First gnathopods in female much 

 as in agilis, carpus somewhat produced and rounded at the infero-posterior angle; second gnathopods 

 of female also resembling those of agilis, hut. the second joint broader and much more strongly and 

 evenly convex in front. Infero-posterior angles of second and third abdominal segments produced 

 into triangular acute points; rami of first uropods shorter than peduncle, those of second pair sub- 

 equal to the peduncle; ramus of last pair equalling or exceeding peduncle and relatively larger than in 

 agilis; telson with a posterior notch, the lobes rounded, spinulous. 



Length, 18 mm. 



Color olive brown to olive green; some individuals reddish brown; antennae reddish brown. 



Cape Cod to New Jersey; coast of Texas. 



This species is readily distinguished from agilis by its larger size, longer antennules, less robust 

 hand on the second gnathopods of the male, the palm of which is not lolied, and the differently 

 shaped second joint in the gnathopods of the female. Its habitat is also different, as it is found com- 

 monly around salt marshes, often far from the shore, among grass and weeds or under objects of 

 various kinds which afford concealment. It crawls and runs more, readily than agilis and is not so 

 ready to hop. 



