420 Rev. A. M. Norman on new Crustacea Amphipoda. 
Jerior antenne ; 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 
jomt of the flagellum. Inferior antenne 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, 1s seen to be finely crenated, or, rather, rasped like a 
file. Peretopods 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. Uvopods : first 
slightly longer than the second, which, again, are slightly longer 
than the last, terminating in simple (¢. 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 Laminarie at Tobermory, in the Island of 
Mull, July 1866. 
I am indebted to the kindness of Mr. G. 8. Brady for the 
figures of Plate X XI. and a part of those in Pl. XXII. 
