NEW SPECIES OF AMPHIPODA. 195 



deep, the first very shallow, produced acutely forward, the seventh produced 

 backward in a small tooth. 



No eyes were perceived. The antennae o£ the single specimen, a female, 

 agree in armature with those figured by Sars for R. helleri (Boeck), both 

 pairs having a great number of the ciliated hairs usually regarded as 

 auditory. In the first antennae the first joint is stouter and a little longer 

 than the second, each having apical teeth, the third joint is about two-fifths 

 the length of the second. The flagellum is scarcely as long as the 

 peduncle, ten- to eleven-jointed, armed with filaments. The accessory 

 flagellum is extremely minute, with an insignificant second joint. In the 

 second antennae the gland-cone is conspicuous, the third joint is about as 

 long as the first in the first antennae, the second joint is decidedly longer^ 

 very slender; the flagellum is seventeen-jointed, yet not quite so long as the 

 peduncle. 



The upper lip has an almost smooth convex distal margin, flanked by a 

 pair of whiskers, from the extremities of which extend a concave line of 

 short hairs. The lower lip was not distinctly made out, but appears to agree 

 with that figured by Sars for R. helleri. 



The mandibles have a strong cutting-plate, that on the left ending in a 

 solid tooth, that on the right bidentate. The accessory plate on the left has 

 an edge divided into six teeth; this plate on the right is shorter, with only 

 four teeth, two of which are notably smaller than the other two. There are 

 four to five spines in the spine-row. The molar is of moderate size. The 

 palp is much shorter than the massive trunk, its third joint tipped with three 

 spines, its length twice that of the first and about half that of the sparsely- 

 spined second joint. This character remarkably distinguishes the present 

 species from others in this genus, which have the third joint of the palp 

 strongly spined and longer than the second joint. There is nothing about 

 the specimen to suggest that the palps are abnormal. 



The first maxillae have a large inner plate carrying two small setae at the 

 distal end of its inner border. The outer plate has nine slender denticulate 

 spines. The palp is long, its first joint twice as long as broad, about two- 

 fifths as long as the sparsely-setose second joint. In the second maxillae the 

 inner plate is rather shorter and broader than the outer, both with setae con- 

 fined to their broad apical borders. The maxillipeds have the inner plates 

 short and broad, the truncate distal margin carrying three spine-teeth and 

 two more slender spines; the outer plate is broad, with very numerous spines 

 round the distal and inner margins. The palp is greatly elongated, and the 

 long second joint has a peculiar appearance because the inner edge is not as 

 usual continuous in a straight line or convex curve, but distally for more 

 than half the total length concave. The third joint is also curved ; this 



