REPOKT ON THE CRUSTACEA MACRURA. 247 



articulate, and fringed with long ciliated hairs, and the coxa carries a mastigobranchia 

 without a podobranchial plume. 



The second pair of gnathopoda (i) is long, slender and pediform ; it is subcylindrical ; 

 the coxa carries a biramose mastigobranchia without a branchial plume attached, but to the 

 membranous articulation are attached two well-formed arthrob'ranchise ; the basis carries 

 a long, biarticulate ecphysis, which resembles that on the first pair of gnathopoda ; the 

 ischium is long, furred with short hairs and armed on the inner margin with a series of 

 curved hook-like spines and corresponding fasciculi of hairs ; the meros is not so long as 

 the ischium, becomes slightly narrowed distally, and is matted with hairs on the inner 

 surface ; the carpos is longer than the propodos, which is longer than the dactylos. 



The first three pairs of pereiopoda are chelate ; the propodos is not broader than 

 the carpos, but the carpos is longer than the propodos ; these three pairs successively in- 

 crease in length as they proceed posteriorly, a circumstance that is due to the gradually 

 increasing length of the carpos, which in each is longer than the meros; the two 

 posterior pairs are subequal, but simple and more slender than the preceding. The first 

 pair is armed on the inner side of the basis with a styliform, anteriorly-directed tooth, and 

 on the outer side with an ecphysis, which is repeated on all the succeeding pereiopoda, 

 but the styliform tooth exists on the second pair only. 



There is a biramose mastigobranchia attached to all the pereiopoda except the 

 posterior pah', and the podobranchial plume is absent from all, as well as from the 

 gnathopoda. The arthrobranchise are present, two being attached to all the pereiopoda, 

 except the posterior pair, and one only existing on the penultimate pair, while a single 

 pleurobranchial plume pertains to each from the first to the fifth pair. The arrange- 

 ment may be represented by the following formula : — 



Pleurobranehias, 

 Arthrobranchice, 

 Podobranehia;, 

 Mastigobranchiae, 



On the vental surface in both our specimens, between the posterior pair of pereiopoda, 

 is a large thelycum, consisting of a dichotomous, calcareous capsule, which extends 

 forwards as far as the base of the antepenultimate pair of pereiopoda, whence projects 

 two large, leaf-like, membranous appendages (PL XXXII. fig. 4 $). They appear to be 

 connected with the internal organs by means of foramina in the floor of the capsule, and 

 have no connection whatever with the fifth pair of pereiopoda. 



The five anterior pairs of pleopoda are formed on one general type. They 

 consist of a large triangulate basisal joint attached to the ventral surface of the pleon, 

 and terminating in two leaf-like branches, both of which are smooth in the median and 

 posterior portions, but strong and multiarticulate at the margins, which are posteriori} 



