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



(03 in.) in length, and has advanced in development as well as in size. It has three 

 pairs of appendages attached to the pereion, or one pair more than is present in the 

 preceding stage (fig. 74). 



The carapace of this specimen is furnished with a small tooth or rostrum in the middle 

 of the frontal margin, and the evidence of its future persistence exists in the presence of a 

 tooth attached to the new or underlying tissue of the next succeeding moult. On the 

 outer angle of the frontal margin a small tooth projects, corresponding with the outer 

 canthus of the orbit, while the tooth previously noticed as standing at the fronto-lateral 

 angle exists in a position further distant from the base of the second antennas, as if some 

 portion of the increase in length attained by the animal was due to growth anterior to this 

 tooth. The somites of the pleon are nearly in the same relative condition as in fig. 1. 



The appendages appear to have advanced a little, but rather in form than in importance. 



The ophthalmopoda are longer in proportion, and the diameter is greater near the 

 distal extremity. 



The first pair of antennas has developed two small spicules, one on each side of the 

 peduncle, as if marking the position of a future articulation, and another at the distal 

 extremity of the peduncle represents the inner flagellum. 



The second pair of antennas has the distal extremity of the scaphocerite furnished 

 with more hairs, and a small tooth exists on the outer margin, defining the limit where 

 cilia cease ; the flagellum has increased in length, but to what extent is not determinable 

 since it is broken in our specimen, in which it is subequal in length with half the carapace, 

 and the peduncle is furnished at the base with a distinct phymacerite. 



The two pairs of gnathopoda correspond with those of the previously described 

 specimen, but differ in being armed with a sharp tooth on the inner distant angle of the 

 basis, and another on the inner margin of the shaft, halfway between the coxal and 

 basisal articulations ; the presence of these teeth may be due to specific distinction 

 rather than to progressive development, as well as the circumstance that the ecphysis 

 and ischial joint each articulate at the extremity of an independent protuberance. 



In this specimen the first pair of pereiopoda is present ; it corresponds in form with 

 the gnathopoda, but is not quite so large, and differs also in having no tooth on the 

 inner margin near the middle of the basisal joint, while that at the inner distal angle 

 exists ; the absence of the former is suggestive of the relation of the teeth to the stage of 

 development. 



There is no evidence of the presence of the pleopoda in this stage, excepting the 

 posterior or sixth pair, which helps to form part of the rhipidura. It consists of a short 

 basal joint supporting two unequal foliaceous rami, the inner of which is the smaller, 

 being scarcely more than half the length of the outer ; it is lanceolate in form and 

 fringed with hairs ; the outer is broader, armed on the outer margin with a strong tooth, 

 and on the inner and distal margin with hairs. 



