CEUSTACEA ISOPODA OF THE ' POECUPINE ' EXPEDITION. 233 



■which is bordered by eight short spines, perhaps of coupling character ; the four 

 following joints are of the usual type and fringed with feathered setee on the outer 

 margin. 



The first gnatbopods are also of the usual type, with a minute apical joint, tlie large 

 opercular joint not showing any signs of its composite nature. The second gnathopod 

 is very slender and as usual closely agreeing in structure with the first perseopod. The 

 second perseopod has suggested the specific name by the spiny erect prominence on its 

 second joint and the squarely produced strong apical process of the third joint, this 

 also being edged with short stout spines ; the fourth joint is also distally widened. 



The pleopods are without setse, and one ramus of the second pair carries a narrow 

 masculine appendage. 



The rami of the uropods are subequal one to the other and to the telsonic segment, 

 the inner, as seems to be customary, being rather more curved than the outer, both 

 being fringed with long setse. 



The length of the specimen was 8 mm. 



Taken by the ' Porcupine ' Expedition in the English Channel, from a depth of 

 539 fathoms (Station 9, 1870, lat. 48° 6' N., long. 9° 18' W.). 



Gnathia schistifro^s. (PL XXIV. B.) 

 Stebbing, Abstract P. Z. S. 1912, p. 43 (Nov. 5th). 



This small species, attaining its greatest breadth at the fifth pergeon segment, is only 

 twice as long as the breadth at that part. The front of the head, which is very much 

 vfider than long, is divided by a small excavation constituting more than a semicircle, 

 the border then sloping on each side to a small outward-pointing process. Behind the 

 processes the sides form two lobes, the eyes just visible on the first pair and the second 

 bulging still more outwards. The second, third, and fourth segments of the perseon 

 are very distinct, successively longer ; the fifth and sixth are probably coalesced, but 

 clearly marked ofi" one from the other, the fifth having a longitudinal median dividing- 

 line, where it is little or not at ail longer than the fourth segment, while at the sides 

 it swells out, to a large extent encircling the somewhat longer but considerably narrower 

 though still large sixth segment. The backward-produced lobes of the latter enfold 

 the small seventh segment and partially also the first pleon segment, which is rather 

 narrower than the second. From this the pleon segments are successively a little 

 narrower, without projecting angles. The telsonic segment has a basal breadth broader 

 than the length, the tapering division little longer than the basal, with a narrowly 

 truncate apex carrying two setules. The surface is much roughened with spicules, as 

 the limbs are with spines and spiniform projections. 



The eyes, rather inconspicuous in dorsal view, are of a somewhat rhomboidal shape, 

 composed of about forty lenses. 



2i2 



