794 



THE VOYAGE OF H.M.S. CHALLENGER. 



The second pair of antennae carries a scaphocerite of the generic form that reaches to 

 the extremity of the rostrum, and a flagellum that is twice the length of the animal. 



The second pair of gnathopoda terminates in a sharp unguis and reaches as far as the 

 distal extremity of the peduncle of the first pair of antennae. 



The first pair of pereiopoda is slender and cylindrical, the propodos being not broader 

 than the distal extremity of the carpos, which is as long as the ischium and meros together; 

 the basis is cylindrical, the inner margin not being developed into a plate as in Bithynis 

 lav. The second pair has the two limbs unequal. The right is the larger and 

 different in form ; it is as long as the animal, and has the meros, carpos, palm of the 

 propodos and dactylos subequal in length, the propodos being subcylindrical near the 

 base and flattened towards the fingers ; the pollex is serrate in the central axis as well as 

 on the inner and outer margin, and armed with a broad, conical cusp about one-third its 

 length from the articulation ; the dactylos resembles the pollex, against which it impinges 

 from the apex to the cusp, where there is a corresponding excavation to receive each. 

 The cusp on the dactylos is smaller and more advanced in position than that on the 

 pollex. The left limb is about two-thirds the length of the right, has the fingers of the 

 chela longer than the palm, the margins parallel and closely impinging throughout 

 their entire length, unarmed, and fringed with long hairs. The three following pairs 

 of pereiopoda terminate in an unguis that is sharp and suddenly narrows from the 

 dactylos ; the propodos is long, cylindrical, and armed with a few short spines on the 

 posterior margin. 



The outer plates of the rhipidura are longer than the telson. 



Female. — Resembles the male in general form but differs in size, and in the relative 

 importance of the second pair of pereiopoda. These are equal in length on the two sides 

 and resemble the smaller limb in the male, excepting that they are not hirsute, the 

 tubercular cusps in the right being reduced to a minimum ; they are about three-fourths 

 the length of the animal. 



Several specimens were laden with numerous, small, oval eggs, some of which appear 

 to be approaching maturity. 



Habitat. — Honolulu. About fifty specimens were bought in the market, having 

 been obtained from the fresh-water rivers on the island. 



