266 Messrs. J. Wood-Mason and A. Alcock on 
the exception of the third pair, in which the sixth and seventh 
joints are in addition fused, and there are hence only five 
distinct jomts; those of the fourth pair are formed as in the 
Crangonide, but, instead of terminating in a subchela, end in 
two equal and movable blades forming a scissors-like organ 5 
those of the fifth pair, which are the shortest and weakest of 
the limbs, bear a probably expansile pencil of sete at the 
distal end of the propodite, which is the functional last joint 
of the limb, the dactylopodite being reduced to a minute 
rudiment ; the sixth, seventh, and eighth pairs form a back- 
wardly increasing series of walking legs; the five last pairs 
are devoid of all traces of epipodites and exopodites. 
The thorax is firmly articulated to the abdomen by a strong 
hinge. 
In addition to the functional gills, which are five pleuro- 
branchiz attached to the posterior thoracic somites from the 
tenth to the fourteenth inclusively, there is present, on the 
arthrodial membranes of the thoracic appendages from the 
ninth to the thirteenth inclusively, a series of five small 
conical papille, which correspond both in number and in 
position to the arthrobranchie of the Glyphocrangonide, and 
are, there is little doubt, to be interpreted as vestiges of gills 
of the same category. 
The body is exceedingly spiny and terminates in front in 
a powerful recurved rostrum, which is toothed on all its four 
margins. 
PSALIDOPUS, gen. nov. 
Body moderately compressed, in shape somewhat like 
FPalemon. Integument firmly chitinized though thin, covered 
throughout dorsally, from the apex of the rostrum to the end 
of the sixth abdominal somite, with long symmetrically 
arranged needle-shaped spines, and between the spines with 
microscopically small sete, which are evenly and regularly 
distributed, and give to the surface a minutely granulated 
appearance up to the base of the caudal swimmeret, upon 
which they become developed into a furry pubescence. 
The carapace is produced in front into a long ascendant 
curved rostrum fully twice its own length measured from the 
frontal to the posterior margin in a straight line; its anterior 
margin is armed on both sides with four spines, which may 
be termed the antennulary, antennal, branchiostegal, and sub- 
branchiostegal spines respectively, and with a stout blunt 
subtriangular deflexed process, against the inner margin of 
which the rudimentary eye-peduncles are firmly retracted ; 
