REPORT ON THE CRUSTACEA MACRURA. 531 



and sixth are the longest, the fifth being shorter than the fourth ; the sixth, which is 

 1*3 mm. long, is nearly equal to the fourth and fifth together. The telson is long, 

 narrow and pointed. 



The ophthalmopoda are short and orbicular, reaching but slightly beyond the apex 

 of the rostrum. 



The first pair of antennse consists of a peduncle of three joints, of which the first or 

 basal joint reaches considerably beyond the extremity of the eye, the second and third 

 joints are short and subequal, and terminate in two slender flagella, the outer of which 

 consists of four short articuli that taper to a point, and the inner is slender and broken 

 off at a short distance from the base. The second pair of antennae carries a long and 

 narrow scaphocerite, that is armed with a small tooth at the outer distal extremity. The 

 flagellum is broken off close to the peduncle. 



The oral appendages have not been examined, as they could not be dissected out 

 without risk to the specimen. 



The first pair of pereiopoda (fig. 3k) is tolerably robust, and terminates in an ovate 

 chela, of which the fingers are about one-third the length of the palm ; the carpos is short, 

 and, like the meros, which is tolerably long, increases in size towards the distal extremity. 

 The second pair of pereiopoda (fig. 3/) is subequal in length with the first, but is much 

 more slender, and also terminates in an ovate chela of which the fingers arc about one- 

 fourth the length of the palm; the carpos is longer than the propodos and quinque-articulate, 

 the distal articulus being the longest. The third and fourth pairs of pereiopoda (figs. 3m, 3n) 

 are alike in size and form, and are subequal to the second pair, but terminate in a short, 

 sharp pointed, and simple dactylos. The fifth pair is broken off beyond the meros, but 

 the portion that remains indicates a much longer appendage: like the preceding, the basis 

 and meros are short and stout, whereas the meros is long, slender, and straight, almost 

 equalling the entire length of the preceding perfect limb. 



The first pair of pleopoda is single-branched, and the four succeeding pairs are biramose. 

 The terminal pair, which forms the outer plates of the rhipidura, is biramose. 



Observations. — The specimen from which this description is taken is evidently an 

 immature animal, and it is not improbable that in a more fully developed condition some 

 parts may vary in their proportions. 



It cannot be the young of Athanas, on account of the form of the first pair of 

 antennse, and of the length of the posterior pair of pereiopoda. 



The animal, when it was captured, was just about to cast its exuvium, which hangs 

 about it as a thin transparent membrane, and the form which I have just described is 

 rather that of the future appearance than of the loose external skin. 



The scaphocerite is visible within the external exuvium, and its form is more perfectly 

 defined than in the latter ; the hairs, which are absent from the envelope, are distinctly 

 visible in their connection with the new structure. 



