92 THE VOYAGE OF H.M.S. CHALLENGER. 



the middle of the first abdominal somite, and they have two or three small secondary 

 spines on their inner edge, while the lateral margin of the carapace, immediately anterior to 

 the base of the postero-lateral spine, has two well-marked lateral spines on each side. 



The hind body is greatly elongated, making about ^ or a little less than | of the 

 total length from the tip of the rostrum. In older larvae the abdomen is depressed, and its 

 width is equal to ^ of the total length. The inner spine of the basal prolongation of the 

 uropod is much longer than the outer, and it has a small tooth on its outer margin, about 

 half way between the base and the tij). The telson is slightly elongated, with six 

 marginal spines, and with secondary dentations between the submedians, and also between 

 the submedian and the intermediate. The eye-stalks are nearly as long as the eyes, and 

 the mouth is a little behind the middle point of the carapace, as measured from the tip of 

 the rostrum. 



In Claus's larva there are three secondary spines on the inner edge of the postero- 

 lateral spine of the carapace^ while there are only two such spines in each of the 

 Challenger sjjecimens. 



In the smallest of the Challenger specimens the dactylus of the raptorial claw has a 

 single marginal spine besides the terminal one, the uropods are very small, and the gills 

 are represented by simple pouches on the exopodites of the first five pairs of abdominal 

 appendages. The carapace, with the rostrum, makes x^o^' ^^^ ^ii^c^ body j^^^, and 

 the width of the abdomen xlnnj of the total length. 



In the older specimen (PL IX. fig. 1) the dactylus is armed with three well-developed 

 marginal spines besides _ the terminal one, the urojaods are nearly half as long as the 

 telson, with the exopodite divided into a broad rounded paddle and a second joint which 

 is fringed with six marginal spines, and the prolongation from the posterior edge of the 

 ventral surface of the basal joint is as long as the exopodite, and ends in a short acute 

 curved outer spine and a much longer inner spine, which has a tooth on its outer margin 

 about half way between the base and the tip. 



The carapace has a well-marked median carina ; the postero-lateral angles of the broad 

 flat abdominal somites all end in acute spines, and there are two submedian carin^e, 

 ending posteriorly in spines, on the dorsal surface of the sixth abdominal. The telson 

 has a median longitudinal carina, and is slightly longer than wide. Its lateral edges, 

 from the anterior edge to the tips of the intermediate marginal spines, are nearly parallel; 

 between the intermediates and the submedians they are inclined inwards and backwards 

 at an angle of 45° with the long axis of the body, while between the submedians they are 

 inclined inwards and forwards. The lateral marginal spine (fig. 2) is nearer to the 

 intermediate than to the anterior edge, and it has a single minute spine internal to its 

 base. The intermediate is longer than the lateral or the submedian, and there are 

 twelve or thirteen small spines between it and the submedian, and there are about twenty 

 very minute spines between the submedian and the middle line. 



