The middle spine of the rosLniin forms a eonsiderable angle- 

 below with the inter-antennulary septum. The most conspicu- 

 ous spines of the carapace in dorsal view . beside those of the 

 rostrum and the pair that Hank the eyes, are three spaced about 

 the middle of each side and two longitudinallv ])laced at about 

 the middle of the back. These have a ])air transversely placed 

 behind them and three pairs strongly diverging- from before 

 backward on either side of them. Behind the rostrum six small 

 spines stretch across the carapace in a shallow curve. There are 

 others round the hind margin, and a few minute prickles occur in 

 various parts. The sternal plastron has rather conspicuot;& 

 prickles across the centre in the three middle divisions. The 

 first segment of the pleon is square, wnth concave sides, the next 

 two are the widest, the fourth narrows to the fifth, which is the 

 same width as the longer sixth and almost semi-circular seventh. 

 From the shape of the narrow pleon and the small size of the 

 chelipcds it may be surmised that the si)ecimcns at present at 

 command are young males- 



The eyes in formalin are reddish brown. 



The second antennae readily fold back. The slender fiagellum 

 is longer than the peduncle. 



The third maxillipeds agree with Alcock's description of those 

 in the other species- The third joint is greatly broader than the 

 fourth, the seventh is longer than either tlie fifth or the sixth. All 

 these joints are spinose, the third and fourth having on the sur- 

 face and at the outer margin rows of denticles in addition to their 

 numerous slender spines. 



The chelipcds are much shorter, but not (as in female and 

 young male of P. ivyviUcthomsoni) more slender than the other 

 legs. They are very spinose, having the fifth joint short, the 

 sixth rather long, with the trunk subequal in length to the finger, 

 w Inch fits closely over the thumb, their finely denticulate margins 

 fitting one into the other. The second legs are between two and 

 three times as long as the chelipcds, with the spinose finger which 

 should perhaps be included among- the characters of the genus. 

 The penultimate joint has the long spines on the inner margin, 

 which are also characteristic in both species. This joint is com- 

 pressed and somewhat dilated, though not at the two extremities. 

 Like the two preceding joints, it is spiny on both margins. It is 

 about three-fourths of the length of the fourth joint, which is 

 about twice as long as the finger- The third pair of legs are much 

 longer but far less spiny, with similar ])roj)Ortions l^etween the 

 joints, except that the sixth, which widens a little distally, rather 

 more nearly approaches the length of the fourth. The fourth 

 pair have the spiny armature inconspicuous, but arc furnished 

 with two rows of long plumose setae on the inner margin of the 

 fifth and sixth joints, and for some way along the finger. They 



