ISOPODA. 
47 
A larger specimen, 1-19 mm. long, is a male, but this was dead when found, and, besides 
some injury, its inside had been almost completely eaten out. On the anterior border 
of the first segment of the metasome are a pair of penial filaments ; these are cylindrical, 
about 5 mm. long, and terminate in an oblique orifice surrounded by a fringe of stiff 
setae. A further sexual character is the long, slender, grooved filament connected, at 
its base only, with the endopodites of the second pair of pleopoda. It is half as long 
again as its endopodite. 
The first antenna arise rather close to the middle line, and comprise a peduncle of 
three joints; the first two are subequal in length, and the third is nearly as long as the 
first two together. The first is slightly contracted in the middle, and has a group of 
stout setse at its inner distal extremity ; the second has a small group about the 
middle of its ventral border, as well as a distal fringe, which is, however, irregular, 
being most accentuated ventrally. The third joint is more slender, swollen, and setose 
distally. The flagellum is not as long as the third joint of the peduncle ; it consists of 
a single joint, strongly curved near the proximal end, and has a band of fine setse 
running alone; its outer border. 
The second antenna arises immediately outside the first; the peduncle is five- 
jointed. The first joint is extremely short, the next two are subequal in size, the 
second having a strongly developed distal fringe ventrolaterally, and the third has a 
ventral mass of setse rather than a fringe; the fourth joint is a little longer than the 
preceding, and, like it, widens distally ; it has a well-developed dorsal distal fringe and 
a mass ventrally which is separable into two groups; the fifth joint is nearly as long 
as the third and fourth together ; it carries along the distal half of the ventral margin 
four groups of setse, besides a dorsal and ventral distal fringe. The flagellum is multi- 
articulate, and half as long again as the peduncle. 
The buccal mass is very prominent; the supporting plate in front bears three 
tubercles, of which the median is very prominent. The epistome is an irregularly 
ovoid plate with'a raised edge, and cleft in the middle. 
The mandible is large and powerful, devoid of a palp; the cutting edge of that on 
the left side is strongly coloured, and overlaps that of the right. 
The first pair of maxillse (fig. 2) consist of the two normal lobes, the inner one 
considerably smaller and weaker than the other. The inner one terminates with three 
rather long and strong setse and several others, much weaker; very minute setse occur 
on both faces of the joint. The outer lobe, at least twice the length and breadth of the 
inner, has eight strong spines distally, and its outer border is fringed with minute setse. 
The second pair of maxillse (fig. 3) are broad, if thin. The inner lobe is constricted 
about its middle, and then forms an ovoid enlargement. The inner and distal border 
of this is furnished with long slender setse ; the two outer lobes are very nearly equal 
in size; they are rounded distally and provided witli long slender setse ; fine setse 
occur on the outer border and the base of the external lobe. 
The maxilliped (fig. 4) is large and strong. The basal joint is broad and stout, the 
