THE CRUSTACEA OE NEW JERSEY. 331 



Remarks. — The distribution is southward along our Atlantic 

 coast from New Jersey as the most northern locality. It was 

 found abundantly at Somers Point in the summer of 1864, 

 and according to its describer it lives among Zostera just below 

 low-water mark. It was also obtained by Stimpson in the har- 

 bor of Norfolk, Virginia, in June, 1853. 



Tribe Astacides. 



Body not compressed, sometimes depressed. Rostrum, when 

 present, not compressed, usually depressed. Integument usually 

 strongly calcified. Abdomen long, not flexed or humped, sym- 

 metrical. Pleura of first abdominal somite much reduced. Tel- 

 son generally quadrangular, occasionally acute. Basal joint of 

 antennular peduncle without "scale" on its outer margin. Olfac- 

 tory setae in distal part ot outer antennular flagellum. Antennal 

 scale, when present, of small or medium size, and never wholly 

 conceals antennal peduncle. External maxillipeds almost al- 

 ways pediform and always much shorter than first pair of 

 thoracic legs. "All five pairs of thoracic legs almost always 

 strongly developed. Variably, as sometimes all, first only, first 

 two, first three, sometimes last alone or again none at all, chelate, 

 and first pair usually much longer and stouter than any of 

 others. Appendages of first abdominal somite, wdien present, 

 uniramous and often modified in male for copulation. Genital 

 openings of male pierced in coxopodites of fifth pair of thoracic 

 legs. 



Key to the siiper-fainilies. 



a. All segments of thoracic sternum usually, but not always, firmly united, 



and abdominal terga overlap one another. astacidea 



aa. Last segment of thoracic sternum independent, and abdominal terga not 



at all, or only very slightly, overlapping one another. thal.-vssinidE-A 



