REPORT ON THE CRUSTACEA MACRURA. 645 



Islands ; depth, 520 fathoms ; bottom, volcanic mud ; bottom temperature, 43°. Six 

 specimens ; five males and one female. Trawled. 



Station 173, July 24, 1874; Lit. 19° 9' 35" S., long. 179° 41' 50" E.; off Matuka, 

 Fiji Islands; depth, 315 fathoms; bottom, coral mud. Seven specimens; three males 

 and four females, two of which are young. Dredged. 



Observations. — The general appearance of the specimens trawled near the Philippine 

 Islands is not very different from that of Plesionilca uniproducta, from off the Atlantic 

 coast of South America, but they differ in having the teeth on the rostral crest more 

 regularly disposed and constant in number ; in both sexes there are six teeth, whereas 

 in Plesionika uniproducta the male has seven and the female only five, and the anterior 

 tooth is separated by a space from the rest, while in Plesionika semilsevis the teeth are 

 disposed at regular but gradually decreasing intervals from the first to the last, as they 

 gradually diminish in size posteriorly. In this species also the third somite is not 

 posteriorly produced in the median line to a point ; and the ophthalmopoda are larger 

 and the ophthalmi more reniform than orbicular. In most other points the two species 

 correspond ; in both the rostrum anterior to the eyes is depressed and then directed 

 horizontally forwards in a straight line, the upper margin being smooth and the lower 

 serrate, with sharp, evenly planted and anteriorly directed teeth, which appear to be a 

 little finer in Plesionika semiltevis than in Plesionika uniproducta. In both, also, the 

 meros in the three posterior pairs of pereiopoda is armed with small and sharp teeth. 

 They were both taken from corresponding depths and from muddy bottoms. 



The specimens taken near the Kermadec Islands are generally more slender, the legs 

 rather longer and the rostrum longer and more rigidly straight, and some of the 

 specimens have the rostral crest adorned with eight teeth, and the ocellus, although 

 clearly defined, is not separated from the dark pigment of the ophthalmus. The length is 

 from three to four inches, and the second antennas is nearly as long again as the animal. 



Comparing the specimens of this species from the different localities with Pandalus 

 -martins, A. Milne-Edwards, taken at from 400 to 1200 fathoms in the Atlantic, the 

 differences are very slight. According to Milne-Edwards' figure the rostrum and the 

 dactylos of the posterior three pairs of pereiopoda are relatively longer, and the 

 ophthalmopoda are not quite so large, and more orbicular. 



A damaged specimen taken at Station 192 appears to belong to this species. It 

 has been attacked by two species of parasitic Isopods ; one, resembling Phryxus hind- 

 manni, was found underlying the carapace, and almost filled the branchial chamber, 

 but without doing much damage to it ; the male was also present, hugging close 

 round the telson of the female. The male of this species had not been determined at 

 the time of publication of the British Sessile-Eyed Crustacea. 



The other parasite found on the same animal closely approximates to Phryxus 



