436 REPORT OF NEW JERSEY SiTATE MUSEUM. 



flagellum, and robust peduncle with basal joint largest. Eye- 

 stalk short, with much more robust base than small eye. Outer 

 maxillipeds fit in oblique chambers, conceal buccal mass, ischium 

 largest joint, carpus a little longer than merus and with set^e 

 distally, also long slender flagella from lower edge with fila- 

 mentous tip extending much beyond end of carpus. Chelipeds 

 subequal, larger and stronger than in next species, fingers conic 

 and a little over one-third length of propodus, cutting-edges 

 approximated and with several rather strong teeth. Carpus 

 and merus smooth, subequal. Ambulatory legs similar, middle 

 pair longest and last shortest. Dactyls of last pair conspicu- 

 ously longer in female than any of other dactyls, in male only 

 slightly so. Lower edges of all carpal and propodal joints 

 densely setous, though apparently more so in male than in 

 female. Segments of post-abdomen not quite equal to greatest 

 width of carapace in female, broader in females with ova, and 

 third and fourth broadest. Post-abdomen in male narrow, 

 width about one-third greatest body width, and slightly gradu- 

 ated wider from telson to basal segment. Color dull brownish, 

 paler below, and tints nearly uniform. Length of carapace 

 9 mm., width 8 mm., in female, and male smaller. 



Remarks. — Distributed along our coast from Cape Cod to 

 Florida and the Gulf of Mexico. It lives in the mussel {Mytiliis 

 edulis). Though very similar to the oyster-crab, it is dis- 

 tinguished by the firmer shell and wide-set eyes. My examples 

 from off Anglesea, and others labeled New Jersey with a query. 

 I have also seen examples from Sea Isle City, Corson's Inlet 

 and Cape May. Adult spawning females have the post-abdomen 

 equally broad as in the oyster-crab. 



Pinnotheres ostreum Say. 



Plate 138. 



Oyster Crab. 



Pinnotheres ostreum Say, Jour. Acad. Nat. Sci. Phila., I, 1817, p. 67, PI. 



4, fig. 5 (female). Inhabits the common oyster of our markets. 

 De Kay, N. Y. Fauna, Crust., VI, 1844, p. 12, PI. 7, fig. 16 (female). 



Found in the common oyster. 



