ISOPODA OF THE 'LIGHTNING' AND OTHEE EXPEDITIONS. 127 



fully developed succeeding pleopods. The extremities of the uropods are also setose, 

 and it is evident that the entire structure of the animal is more adapted for active 

 locomotion than that of the female. 



Length of female 13 millim. (or half an inch), of male 17 millim. 



Taken by the ' Porcupine ' expedition in 1870, in 740 fathoms, off the coast of 

 Portugal. (Station 17 a, lat. 39° 39' N., long. 9° 39' W.) 



The specific name has reference to the elongated pleon with its well-marked 

 segmentation. 



2. Anthelura abyssorum, n. sp. (Plate XXVII. fig. ii.) 



Head and person of nearly equal width throughout ; second segment of the latter 

 scarcely at all constricted behind. The whole of the segments smooth above, and 

 devoid of all furrowing and pitting ; last segment of peraeon half as long as the pre- 

 ceding segments of pleon (ii. pi., d), very clearly defined, and (exclusive of telson) sub- 

 equal in length to penultimate segment of peraeon. 



The antennae (ii. c, d) have the joints of the peduncle in both pairs flattened, the 

 lower pair touching each other with the compressed inner margins, and appearing 

 between the upper pair, as in Anthelura elongata ; flagella of both pairs many- 

 jointed. 



First gnathopods (ii. gn^) having basos short and very thick ; ischium scarcely longer, 

 and not so broad ; cup of meros well rounded ; carpus small as usual, bearing five or 

 six spine-like setae ; hand about twice as long as greatest breadth ; palm concave, bearing 

 about eight slender spine-like setae. 



Second gnathopods (ii. gn^) having basos and ischium more slender than in first 

 pair ; meros of similar form ; carpus edged with several spine-like setae and one spine ; 

 hand elongate-ovate, palm with three spines and a few setae. 



Last peraeopods (ii. prp^) having the propodos half as long again as the carpus, and 

 the dactylos subequal to the carpus ; carpus and propodos each furnished with two 

 forked spines on their anterior margin. 



First pleopods large, covering the whole of the remaining pleopods, against which 

 they are closely pressed. 



Uropods (ii. pi. d and ii. pi. l) with outer and upper plates wide apart dorsally, 

 broadly triangular or spear-shaped, longer than wide, and as long or nearly as long as 

 the inner plate, which is very similar in form but narrower, with well-rounded extre- 

 mity ; both are tipped with a few setae, which are, however, very easily abraded. 



Telson much depressed, broadly lanceolate, apex rather acute, about equal in length 

 to the uropods. 



Length 9 millim. (or about three sixteenths of an inch). 



Dredged by H.M.S. 'Valorous' in 1875 (Station 8), in 1750 fathoms, near the 



entrance of Davis Strait, lat. 59° 10' N., long. 50° 25' W. 



U2 



