188 DE. C. CHILTON ON THE SITBTEEEANEAN 



The sixth segment is completely coalesced with the telson, forming a somewhat conical 

 tail-piece, which ends posteriorly in a small projection broader than long, its upper angle 

 at the extremity sharp and tipped with a few small setae, the lower angle being rounded 

 and free from setse. Below this projection the inferior margin on each side is slightly 

 irregular, more or less dentate, and is fringed with spinules. The posterior margin in 

 front of the articulation of the uropoda is convex and bears four stout spiniform setae. 



The upper antennce (PI. XVI. fig. 2) consist of about 9 or 10 joints, of wliich the 

 three at the base may be considered the peduncle, although there is little or nothing to 

 distinguish them from the succeeding joints. The first and second joints are subequal 

 and somewhat larger than the tliird ; all three bear several small setse at the distal end ; 

 the first three joints of the flagellum are subequal and a little shorter than the last 

 joint of the peduncle ; the remaining joints are longer and thicker, being usually 

 considerably swollen, especially towards the distal end, the swelling being chiefly due to 

 a thickening of the chitinous integument ; the penultimate joint is usually the thickest, 

 the terminal one being small. The joints of the flagellum bear a few minute spinules 

 distally, and the last four joints have in addition one or two small "olfactory cylinders." 



The number of the joints in the antennie and their relative sizes are subject to 

 considerable variation. The one drawn (PI. XVI. fig. 2) has the terminal joints less 

 swollen than usual ; the penultimate joint is slightly constricted at the middle and 

 bears two groups of "olfactory cylinders;" hence it probably represents two joints, and 

 in that case this antenna would contain altogether ten joints. The other antenna of the 

 same specimen was more normal; it also contained ten joints, and those toward the end 

 were more swollen, the antepenultimate being the largest. 



he lower antennce (PI. XVI. fig. 3) are about half as long as the body. The peduncle 

 is somewhat longer than the upper antennae. The first two joints are short and subequal ; 

 the third is about as long as the first and second together, curving slightly upward, the 

 upper margin being concave and the lower convex, while there are two small groups of 

 setae on the lower margin and one on the upper margin at the extremity ; the fourth 

 joint is half as long again as tlie third, having a few spinules along each margin and 

 a tuft at the extremity in the middle ; the fifth joint is considerably longer than the 

 fourth, bearing three or four small tufts of setae along each margin and tufts of longer 

 setae at the extremity. The flagellum contains about 30 joints, each bearing at the 

 extremity a circlet of setae about half as long as the joint from which they spring; some 

 are placed singly, others in small tufts. At the base of the flagellum each joint is as 

 broad as long, but they gradually become longer and narrower until at the end each joint 

 is about four times as long as broad. 



The upper lip (PI. XVI. fig. 4) is rather large and strong, being thick and chitinous. 

 It is broader than long, rounded distally, the middle of the distal margin very slightly 

 produced ; the extremity is covered very densely with fine short setae, directed chiefly 

 towards the centre and forming a thick fur. 



The mandibles (PI. XVI. figs. 5, 6) are very similar in general structure to those of 

 Phrentoiciis tmstralis [26, pp. 156, 157, pi. xxiii. figs. 5 and 5rt]. In a lateral view of 

 the head the large basal joint is seen extending along the anterior portion of the lower 



