264 BULLETIN OF THE 



in breadtli. The front is nearly straight, the branchial regions expanded 

 laterally so as to form a prominent shoulder at the point where they meet the 

 hepatic areas. A row of small, irregularly disposed spines on the sides of the 

 carapace. The second and third pairs of maxillipeds (Figs. 6, 7) have the same 

 structure as in adult Pinnixce, the terminal segment of the inner limb being 

 ai'ticulated with the penultimate segment near the proximal end of the latter, 

 in such a fashion as to form a sort of didactyle claw. 



The chelae are didactyle, the dactylus closing against a long process of 

 the antecedent segment. The following pairs of ambulatory appendages are 

 extremely long, the last pair being much smaller than the rest, as in the adults 

 of this genus. 



The abdomen is small, closely folded against the sternum, and not used as a 

 swimming organ. It carries four pairs of appendages (Fig. 3), which consist 

 of a basal segment which supports two branches. The outer branch is much 

 larger than the inner, and bears about nine setas on its border. The telson is 

 broader than long, its posterior margin regularly convex and fringed with setae. 



Blotches of dark pigment, of dendritic forms, occur on the carapace, stemiun, 

 and abdomen, arranged as represented in Figs. 1, 2. 



The young crabs underwent hardly any change during my stay at Newport, 

 and it is impf)ssible to determine to which of the several species of Pinnixa, 

 described from the eastern coast of the United States, these immature speci- 

 mens belong. According to Smith, the only species found on the New Eng- 

 land coast is Pinnixa cylindrica White.* I found no adult specimens at New- 

 port. 



Since the above account was prepared, T have received, through the courtesy 

 of Professor Smith, a pair of adult Pinnixce from Buzzard's Bay, Massachusetts, 

 and a few zoeee " hatched at Noank, Connecticut, August 3, 1874, from eggs 

 of a specimen apparently exactly like the adults sent." I identify the adults 

 with Pinnixa chcetopterana Stimpson t (Plate V. Fig. 8, chela of male ; Fig. 

 9, chek of female). The zoese (Plate IV. Figs. 1-4) are less than a milli- 

 meter in length. The spines of the carapace are proportionately shorter than 

 in the older zoea described above, the swimming-feet and abdomen longer. 

 The appendages back of the second pair of maxillipeds are wanting. The 

 abdomen is very like the abdomen in the older zoea, but has a small, trian- 

 gular, terminal piece (Fig 2 b) between the seta; of the telson. 



Professor Smith informs me that he observed, in 1875, the direct change 



* Report upon the Invertebrate Animals of Vineyard Sound and Adjacent Waters, 

 with an Account of the Physical Features of the Region. By A. E. Verrill and S. I. 

 Smith. In Baird's Report on the Condition of the Sea-Fisheries of the South Coast 

 of New England in 1871 and 1872, p. 546. 1873. 



t Notes on North American Critstncea in the Museum of the Smithsonian Insti- 

 tution. No. II. Ann. Lye. Nat. Hist. N. Y. Vol. VII, p. 235. 18G2. 



