REPORT ON THE CRUSTACEA MACRTJRA. 315 



The metastoma is double, somewhat pear-shaped, and flattened against the posterior 

 walls of the mandibles. 



The first pair of siagnopoda is three-branched ; the first two branches are flat, strong, 

 and fringed at the inner margin with short hairs and strong spines ; the third is short, 

 terminating in an ovate distal extremity that carries several long and simple hairs, while 

 the outer margin is fringed with plumose cilia, and at the base there is a fasciculus of 

 ciliated hairs. 



The second pair of siagnopoda is three-branched, two of the branches are flattened, 

 subfohaceous and biramose, and each is tipped with short stiff hairs ; the third is 

 short, flat and pointed, and attached to the coxal joint is a large mastigobranchial plate 

 that projects anteriorly beyond the extremity of the limbs, and posteriorly, while short, 

 is broadly expanded. 



The third pair of siagnopoda is five-branched ; the coxa is short, studded upon the 

 inner side with short stiff hairs, and carries externally a large, broad, mastigobranchial 

 plate ; the second or basis is short and carries on the inner side a broad, rigid, slightly 

 flexed plate that is thickly fringed with stiff hairs, and on the outer side a long and 

 flat ecphysis ; the three next joints articulate terminally, the last being ovate, and all 

 are fringed with numerous, long, ciliated hairs. 



The first pair of gnathopoda is subpediform ; the coxa carries a well-developed 

 mastigobranchia and podobranchial plume ; the basis is very short and carries a small 

 ecphysis ; the ischium is equally short, and closely associated with the basis ; the meros is 

 long, stout on the outer side and thin on the inner, where it is thickly fringed with hairs ; 

 the carpos is triangulate, stout, and thickly covered with hair; the propodos and dactyl os 

 are terminally articulated, and lie reflexed against the meros ; they are widest at the 

 carpal joint, and taper gradually to the unguiculate extremity, which is armed with 

 three strong teeth, of which the most robust is at the extremity. 



The second pair of gnathopoda is long and pediform; the coxa carries a mastigobranchia 

 with a podobranchial plume attached; the basis carries a very small and slender ecphysis, 

 the ischium is long and narrow ; the meros is half the length of the ischium, narrow and 

 subcylindrical ; the carpos and propodos are equal in length to the ischium, but more 

 slender^and cylindrical, and the dactylos is slender, tapering, and slightly shorter than 

 the propodos, and has the under surface thickly covered with hairs. 



The first three pairs of pereiopoda are subequal, but not large, nor differing from 

 those of Penasus proper ; they each support well-developed mastigobranchial plates and 

 well-developed plumes. The podobranchise and the arthrobranchise are the largest, the 

 pleurobranchise being small but not rudimentary. 



The posterior two pairs are long and slender, reaching as far forwards as the 

 extremity of the smaller flagellum of the first pair of antennas. 



In the female the oviducts open on a flattened tubercular process, situated on the 



