170 Messrs. J. Wood-Mason and A. Alcock on 



The first and second pairs of legs are dissimilar both in 

 form and structure. 



The first pair is the shorter, and their claws are shaped 

 much as in Pastphae. The inner edge of the dactylopodite 

 is unarmed, but is raised into a sharp lamellar cutting-edge ; 

 that of the prolonged part of the propodite, on the other hand, 

 is armed throughout witli minute acicular spines of tolerably 

 uniform size and all slanting towards the apex of the joint. 



The second pair is much the longer, and their claws differ 

 in form in the different species and would appear to be 

 unequal on the two sides. The inner edge of both dactylo- 

 poditic and propoditic elements of these claws is armed with 

 minute spines similar to those of the first pair, and, in addi- 

 tion, at intervals with much longer ones (three or four ti nes 

 as long) of the same form. 



The third and fourth pairs of legs are alike. They are 

 greatly reduced in thickness, but little if anything in length, 

 forming long setaceous filaments of excessive tenuity and 

 fragility. 



The fifth pair of legs is the shortest of all and is much 

 stouter than the third and fourth and much slenderer than the 

 first and second ; it is, in fact, in point of thickness about 

 interinediate between the two sets of legs. They are set on 

 and directed in the manner which seems characteristic of the 

 family. Their propodite bears at the distal end of the lower 

 surface a conspicuous whisp of longish setse, which is directed 

 towards the apex of the joint, while the dactylopodite is 

 covered below with a dense brush of short spiny sette, and is 

 evidently intended to fold back against the propoditic whisp, 

 so as to form therewith a sort of prehensile subchela. 



All the legs possess the full number of joints and all are 

 furnished with exopodites. The exopodites of the first pair 

 of legs are small and inconspicuous, but those of the second 

 to the fifth pairs are long and excessively fine articulated 

 setaceous filaments, which form a gradually increasing series 

 to the fourth, the fifth being suddenly much longer and fully 

 equalling in length the third or fourth pairs of legs. They 

 are all very sparsely clothed with long, lax, obsoletely plu- 

 mose setas, and are all produced at the base into a little 

 tongue-shaped spur. 



The first to fifth pairs of abdominal appendages are remark- 

 able for the enormous inequality of their two branches, as 

 well as for the excessive tenuity of the outer branch, which, 

 in the case of the second pair, is in one species no less than 

 twenty-four times the length of the inner, which is quite 

 minute ; the exopodites of the abdominal appendages, in fact, 



