ISOPODA. 47 



A larger specimen, 119 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, ;ind 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 setae at its inner distal extremity ; the second has a small group about the 

 middle of its ventval 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 nagellum 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 setae 

 running along 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 setae 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 setae, 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 maxillae (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 setae and several others, much weaker ; very minute setae 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 setae. 



The second pair of maxillae (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 setae ; ihe two outer lobes are very nearly equal 

 in size ; they are rounded distally and provided with long slender setae ; fine setae 

 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 



