No. 26.] ARTHROSTRACA OF CONNECTICUT. 73 



This Species occurs on sandy shores, where the animals burrow 

 near low-water mark with great dexterity, being by far the most 

 rapid burrowers among the Amphipoda. It is also occasionally 

 found under stones in sandy places, and is dredged in shallow 

 water. 



It can not easily be confused with any other Amphipod be- 

 cause of its broadly expanded pereiopods devoid of dactyls. 



PHOXOCEPHALID^. 



Rostrum projecting like a hood over bases of antennae. 



Coxal plates rather large. 



First antennae with accessory flagellum well developed. 



Mandibles with cutting edges distinctly developed, molar 

 tubercle not large; palp large. First maxillae with inner plate 

 small, palp uni- or biarticulate. Maxillipeds i with plates small 

 and palp large. 



First and second gnathopods generally similar in form, sub- 

 chelate, large. Fourth pereiopod the longest. 



Terminal uropods often varying sexually, outer ramus the 

 longer, biarticulate. 



Telson deeply cleft. 



Phoxocephalus Stebbing. 



Head with acute hood. 



First antennae shorter than second which in the male are very 

 elongated and slender and bear calceoli on the flagellum. 



Mandibles with molar tubercle distinctly developed ; palp well 

 developed. First maxillae with very small uniarticulate palp. 

 Second maxillae with the plates nearly equal. Maxillipeds with 

 outer plate scarcely larger than inner; palp with fourth joint 

 slender. 



Gnathopods unequal, the posterior ones being the larger. 

 Third pereiopods with basal joint laminarly expanded; last pair 

 with basal joint very large. 



Last uropods in female with inner ramus naked and much 

 shorter than outer; those in male much larger with both rami well 

 developed, lanceolate, furnished marginally with ciliated setae. 



Lobes of telson narrow. 



