REPORT ON THE CRUSTACEA MA CRURA. 07!) 



behind which, in advance of the posterior margin, there is in the median line a small 

 circumscribed tubercle. The frontal margin of the carapace has the outer canthus of the 

 orbit defined by an obtuse point within the first antennal tooth, which is small, as is also 

 that of the second. 



The ophthalmus is small and round, being smaller in diameter than the ophthalmopod 

 on which it stands (fig. 3a). 



The first pair of antennae has the peduncle subequal in length with the rostrum ; 

 the first joint, which equals the length of the other two, is depressed to a greater extent 

 than is necessary to receive the eye and has no blepharos or fringe of reversely directed 

 cilia on the anterior upper surface, but carries a long stylocerite, sharp at the apex but 

 horizontally dilated within the extremity. The flagella are slender and about twice the 

 length of the carapace, the outer and. upper in the male being a little more robust than 

 the inner. 



The second pair of antennae carries a long and narrow scaphocerite that reaches 

 considerably beyond the rostrum, and the flagellum is longer than the animal. 



The branch attached to the basis al joint of the first pair of gnathopoda is long, and 

 that attached to the second is slender, single-jointed and flexile. 



The first pair of pereiopoda is less robust and shorter than the second pair of gnatho- 

 poda, and terminates in a lanceolate dactylos. The second pair carries a tolerably robust 

 chela and the articulations of the carpos are rather distant. The three posterior pairs 

 have the posterior margin of the ischium and meros sparsely armed with strong spine - 

 like teeth. The coxal joint of the last three, as shown most distinctly in the posterior 

 pair, has a broad and flat posterior plate that checks the backward movement of the legs. 

 This joint in all the pereiopoda except the posterior carries a small rudimentary 

 mastigobranchia, which terminates in a small hook. The mastigobranchia belonging to 

 the second pair of gnathopoda exhibits a peculiarity that exists in most of its congeners, 

 but is very pronounced in this species. Instead of springing directly from the coxa as in 

 all the pereiopoda it arises vertically from the centre of a rigid and scarcely articulating 

 basal plate which springs perpendicularly from the coxa and penetrates between the 

 branchial plumes, separating that of the first pair of gnathopoda from those of 

 the second. 



The pleopoda are biramose and subfoliaceous ; the anteiior branch carries on the 

 inner side a long stylamblys, subapically furnished with a corona of cincinnuli, except 

 in the first pair, which has the inner and anterior branch shorter and more mem- 

 branous, and terminates in a point which carries the stylamblys, the margins being 

 furnished with thickly set plumose cilia. The outer branch of the posterior pair, which 

 helps to form the rhipidura, has two longitudinal ribs : the outer runs diagonally from the 

 base to the outer angle of the diaeresis and terminates in two small teeth, the second is 

 central and contains the muscles that act upon the terminal plate. 



