THE CRUSTACEA OF NEW JERSEY. 209 



deeply bilobed. Cephalon truncated anteriorly, and buccal mass 

 greatly projects inferiorly. Eyes comparatively small, situated 

 near dorsal face of cephalon. Superior antennae generally very 

 much shorter than inferior, without any accessory appendage. 

 Inferior antennae more or less pediform, peduncle rather elong- 

 ated and its basal joint coalesced with cephalon. Anterior lip 

 large, rounded. Epistome applanated. Posterior lip membra- 

 nous, with projecting lateral corners. Mandibles without palps, 

 very powerful, cutting'-edge divided into two superposed lamellae 

 which strongly denticulate on edges, molar expansion large and 

 thick, and between both a series of curved setae. First pair of 

 maxillae with palp obsolete or nearly so, masticatory lobe well 

 developed and furnished at tip with several strong denticulated 

 spines, basal lobe very narrow, with two short and densely ciliated 

 curved set^e at tip. Second pair of maxillae with lobes rather 

 broad and densely setiferous on inner edge. Maxillipeds with 

 masticatory lobes very small and rounded, basal lobes mu'ch 

 larger and armed at tip with short teeth and bristles. Palp rather 

 large, joints complanated and short hairs at edges. Gnathopoda 

 of various structure, second pair more generally different in 

 two sexes. Peraeopoda rather strong, edged with tufts of short 

 spines, three posterior pairs successively increasing in length and 

 having basal joint broad and laminar. Branchial lamellae gen- 

 erally very small and vesicular in form. Pleopoda poorly de- 

 veloped. First two pairs of uropoda strong, with both ram'i, as 

 also basal part, denticulated. Last pair very small, with only a 

 single minute ramus. Telson short and thick. 



The members of this family are more or less adapted to a 

 terrestrial life, and when out of the water progress by quick 

 leaps or abrupt hops. Genera several. Of the genus Hyalella, 

 Hyalella knickerbockcri (Bate) was based on specimens in the 

 British Museum received from Say and ascribed to North 

 America, "in brooks, under stones." Similarly another species, 

 Hyalella sayi (Bate), was also described from North America. 

 Their admission to the fauna of New Jersey has never yet been 

 demonstrated. 



14 MU 



