REPORT ON THE CRUSTACEA MACRURA. 283 



The basis does not cany a branch, or ecphysis ; but the coxa supports a short mastigo- 

 branchia that is broad for a short distance from the base, and then suddenly narrows to 

 a slender lash. At the base, near the articulation, is a well-developed podobranchial plume. 

 The second pair of gnathopoda (/) is pediform and seven-jointed. The basisal joint 

 carries a long and slender ecphysis, and reaches nearly to the extremity of the sixth 

 joint or propodos. There is no mastigobranehia attached to the coxa, but two arthro- 

 branchise arise from the membranous articulation. 



The first pair of pereiopoda is short, slender, and chelate, and carries a pedunculated, 

 forked mastigobranehia without any podobranchial plume. The second and third pairs 

 increase respectively in length, a circumstance that is chiefly due to the increased 

 length of the carpos. They each carry a pedunculated and forked mastigobranehia 

 similar to that of the first pair. The fourth and fifth pairs are long, slender, and 

 terminate in a styliform dactylos, the posterior pair being much the longer of the 

 two. Both of these are without either mastigobranehia or podobranchial plume ; whereas 

 the penultimate has two arthrobranchife, one of which, the anterior, is in a rudimentary 

 condition. The general arrangement may best be understood by the table given under 

 the description of the genus. 



The ventral surface of the female, in all the specimens in the collection, shows the 

 third pair of pereiopoda with a protuberance directed obliquely backwards, on the inner 

 side of which the oviducts open and come into contact with each other in the median line : 

 behind these is a deep depression, which is chiefly caused by an elevated process that 

 supports the coxal articulation of the penultimate pair of pereiopoda. Posterior to this, 

 approaching each other and slightly raised anteriorly in the median line, and posteriorly 

 diverging outwards, are two long, slightly curved protuberances, the posterior extremities 

 of which correspond with the articulation of the ultimate pair of pereiopoda. 



In the male the anterior pair of pleopoda carries a petasma that is longitudinally folded 

 into a cylindrical form, with the posterior surface open ; the terminal extremity is lobed 

 and supplied with four hook-like processes, two on each side. In the female this pair of 

 pleopoda has only one branch, and a rudimentary process attached to the inner side of 

 the peduncle. In the male the second pair has two unequal branches, and at the base of 

 the inner or smaller is a small button-shaped process. The succeeding pleopoda correspond 

 in both sexes, and gradually diminish in size. The posterior pair, that forms the lateral 

 plates of the rhipidura, are long and narrow, both reaching beyond the extremity of the 

 telson. The diaeresis of the outer branch is reduced to an obsolete condition, being 

 represented only by the muscular attachments which are situated near the body of the 

 animal, and the small tooth on the outer margin which generally corresponds with its 

 outer limit. 



