420 Rev. A. M. Norman on new Crustacea Amphipoda, 



ferior antennae ; the basal joint is thicker than the second, to 

 which it is subequal in length ; the third joint is shorter and 

 more slender than either of the preceding; flagellum 9-10- 

 jointed, of about the same length as the peduncle ; the secon- 

 dary appendage minute, two-jointed, not so long as the first 

 joint of the flagellum. Inferior antennce stronger than the 

 superior ; both pairs are furnished with scattered hairs, but no 

 spines. The mandible is furnished with a three-jointed palp. 

 The first gnathopods have the hand equal in length to the 

 wrist, but broader, and widening from the base to the extre- 

 mity ; the palm is oblique and concave ; the nail well deve- 

 loped, simple, and extending rather beyond the palm. The 

 second gnathopods have the wrist very short ; but the hand 

 is greatly developed, and is as long as the whole of the 

 rest of the leg, of an oblong form, having a slightly concave 

 palm extending its whole length, bounded at the supero-anteal 

 corner by a tooth-like process, which, however, is only deve- 

 loped in mature specimens, being wholly absent or evanescent 

 in the young ; the distal portion of the palm is furnished with 

 two large teeth ; finger large, strong, curved, fully as long as 

 the hand ; its inner margin, under a high power of the micro- 

 scope, is seen to be finely crenated, or, rather, rasped like a 

 file. Pereiojpods having the same general characters as those 

 of the genus Microdeuteropus^ last pair long, a tuft of hair at 

 the base of the nail, as is usual in the last-named genus. 

 Telson tubular, tipped with two or three hairs. Uropods : first 

 slightly longer than the second, which, again, are slightly longer 

 than the last, terminating in simple {i. e. not hamate) spines ; 

 last pair having only a single branch. 



The female differs widely from the male in the structure of 

 the second pair of gnathopods, which, instead of being the 

 immensely developed organs of that sex, are scarcely larger 

 than the first pair, from which they differ chiefly in the form 

 of the wrist, which is very short, broader than long, and some- 

 what cup-shaped, the infero-posteal angle being projected into 

 a rounded lobe. 



Length hardly exceeding a tenth of an inch, it being one of 

 our smallest Amphipods. Colour yellowish, more or less 

 covered with umber-brown spots ; these spots are seen under 

 the microscope to be dendritic ; they often form bands across 

 the segments, or at times so coalesce as to make the whole 

 animal appear of a brown colour. 



Found among Laminarice at Tobermory, in the Island of 

 Mull, July 1866. 



I am indebted to the kindness of Mr. G. S. Brady for the 

 figures of Plate XXI. and a part of those in PL XXII. 



