236 DE. C. CHILTON ON THE STJBTEEEANEAN 



Detailed Description. 



In this species the male differs in a very marked manner from the female, being of 

 considerably larger size, differing also in the antennae and particularly in the gnathopoda. 

 The males are very much rarer than the females ; I have seen only about half a dozen 

 males altogether, while I must have seen hundreds of specimens of the female. It will 

 be convenient to describe the male first, and afterwards to point out more in detaU the 

 characters in which the female differs from the male. 



The body (PI. XXII. fig. 1) is smooth, fairly stout. The head is longer than the first 

 segment of the peraeon ; the segments of the perseon subequal ; first three segments of the 

 pleon considerably longer than the last segment of the peraeon. The side-plates of the first 

 four segments of the peraeon are nearly as deep as their respective segments. The 

 inferior margins of the first three segments of the pleon are regularly rounded and have 

 no setae. 



Eyes. There is no external sign of the eyes. 



The npper antenncB (fig. 2) are more than two-thirds as long as the body. The 

 peduncle has the first joint stout, about half as broad as long, with a few minute setae 

 scattered over it, the lower surface with a row of about seven or eight short setae, and 

 at the extremity three or four long auditory setae. The second joint is about two-thirds 

 as long as the first, but not much more than half the width ; the lower surface bears a 

 few minute spinules and some longer setae at the extremity ; on the inner surface, towards 

 the upper side, is a row of three or four " calceoli," at the base of each of which are two 

 or three simple setae. Third joint about half as long as the second, similarly furnished 

 with calceoli and setae. There is a minute secondary appendage on the inner surface, 

 consisting of a single small joint tipped with two setae. The flageUum is more than 

 twice as long as the peduncle, and consists of a great number of joints, of which about 

 the first third bear calceoli arranged in two rows, the first being situated on the inner 

 surface towards the upper margin, the other also on the inner surface but lower down, 

 and being on joints of the flagellum alternating with those that bear the first-mentioned 

 row of calceoli, the part of each joint that bears a calceolus is somewhat produced into a 

 small rounded prominence, which bears three or four simple setae as well as the 

 calceolus. Towards the extremity of the flagellum the joints become much m.ore 

 elongated and cease to bear calceoli. Olfactory cylinders are found on the joints which do 

 not bear calceoli, as well as on some, if not all, of those which do bear calceoli. 



The lotcer antennce (fig. 4) are about half as long as the upper, both the peduncle 

 and the flageUum being rather stout. The " gland-cone " attached to the second joint 

 is rather large and prominent, and bears two separate setae at some little distance from 

 the apex. The short third joint is grooved below, and bears at the extremitj^ of its 

 lower margin two simple setae ; its articulation with the fourth joint is very oblique. The 

 fourth joint is rather broad, nearly half as broad as long ; its upper margin bears thi'ee setae 

 in slight serrations ; there is a tuft of four setae in the middle of the lower margin and 

 another larger tuft at the extremity. The fifth joint is slightly longer than the fourth ; 

 on the upper surface it bears four or five small tufts of setae, and on the lower margin 



