EEPOKT ON THE AMPHIPODA. 1037 



transverse dorsal depression, which facilitates its telescoping with the segment before it ; 

 the partially coalescent fifth and sixth segments have a similar depression between them. 



Eyes round, simple, the upper pair near the rounded upper corner of the head, the 

 lower pair close to the lower corners. 



Upper Antenna. — First joint short ; second more slender, but much longer, with 

 about a dozen long slender spines on the lower margin ; the third joint nearly as long 

 as the first, not distinguishable from the joints of the flagellum, of which there are ten, 

 together longer than the peduncle, having setiform spines on the lower margin. 



Lower Antenna; much longer than the upper, about equal to the length of the animal. 

 The first two joints short and comparatively broad, the third a little longer than the 

 second, directed upwards close to the lower margin of the head, beyond which it scarcely 

 reaches ; the fourth joint more slender, longer than the whole peduncle of the upper 

 antennae, with slender spines at a few points of the under margin ; the fifth joint 

 thinner and shorter, similarly armed ; the flagellum longer than the peduncle, of thirty- 

 four slender joints, armed with slender spines, many of them long. 



The Upper Lip appears to have distally a faint unsymmetrical emargination, with 

 very slight ciliation. 



Mandibles. — The cutting plate bent at almost a right angle to the upper edge of the 

 trunk, divided into five teeth, of which the uppermost extends beyond the rest ; on the 

 left mandible there appear to be two extra denticles on this largest tooth ; the secondary 

 plate is narrow, apically divided into three, or perhaps five, teeth ; it is of slighter 

 structure on the right than on the left mandible, in each being more or less parallel to the 

 principal plate ; the spine-row is of thirteen or fourteen closely set, backward-curving 

 spines, which are denticulate and nearly evenly broad till they suddenly narrow to the 

 apex ; the molar tubercle is prominent, its oval crown set with strong denticles, and having 

 a long low ridge with an angled margin just above its distal border ; a broad process rises 

 beside the base of the palp ; the palp is longer than the trunk, set over the molar tubercle, 

 its first joint more than twice as long as broad, its margins carrying two or three small 

 spines ; the second joint twice as long as the first, with slender spines at five or six 

 points on each of two edges ; the third joint is longer than the first, but shorter than the 

 second, very thin, the hind margin convex, the narrow apex carrying two or three spines, 

 and the straight front margin having three pairs. 



Lower Lip. — The principal lobes deeply but not widely divided and strongly ciliated 

 on the inner margins, the ciliation passing round only the inner portion of the rather 

 flatly convex distal margins ; the inner lobes reaching nearly as far forward as the 

 principal ; the mandibular processes very short, with the narrow rounded apices slightly 

 converging. 



First Maxilla;. — Inner plate small, with a short seta or spine on the narrow apex, and 

 a long plumose seta some way below the apex on the inner margin, which below this is 



