242 CEYLON PEARL OYSTER REPORT. 



margin. The hand tapers gradually to the base of the dactylus without a palm, the 

 hind margin finely pectinate with 4 spines and as many pairs of unecpial setae. 

 Dactylus about one-fifth the length of the hand, curved. Side-plates small, oval 

 below (fig. 5. gn. 1 ). 



Second gnathopods long and slender, the joints of almost uniform width throughout ; 

 the 1st slightly curved, about 6 times as long as wide : the 2nd twice as long as the 

 3rd ; the wrist about equal to the two last named, margins straight, the hind margin 

 setose; hand about two-thirds as long as the wrist, margins parallel, the hind margin 

 with long setre directed forwards. Side-plates nearly as long as the 1st joint, about 

 twice as deep as wide, oval below (fig. 5. gn. 2 ). 



First and 2nd peraeopods : 1st joint about as long as the next three ; 2nd very 

 short, 3rd, 4th, and 5th subequal ; dactylus strong, about half as long as the preceding 

 joint. Side-plate of the 2nd about as wide as one-fourth of the length of the whole 

 body; hind margin excavated above and rounded below; front margin with tlie lower 

 angle produced and acute (fig. 5. pp. 2 ). 



The remaining perreopods have the 1st joints expanded and serrate behind, the 

 lower margins in the 3rd and 4th rounded, in the 5th almost straight ; front margins 

 spinous ; 3rd joints spinous before and behind. 



The uropods are damaged ; the 1st pair extends the furthest, then the 2nd, which 

 have the peculiar character shown by Stebbing in his figure of A. macrophihalrnus 

 (' " Chall." Rep.,' Plate 29). The rami of the 3rd pair are straight and lanceolate. 



The telson reaches to about one-third of the length of the peduncle of the 

 3rd uropods, and is cleft for about one-third of its length, the cleft dehiscent. 



This species may be distinguished by the acute anterior angle of the 4th side-plate, 

 and by the straightness of the wrist and hand of the 2nd gnathopods. It may be 

 identical with Glycerina affinis, Chilton ('Trans. N.Z. Institute,' vol. xxiv., p. 2. 

 Plate XL VII.), but the description of that species is not sufficient to determine the 

 point. 



Lysianax, Steebing, 1888. 

 Lysianax cinghalensis, Stebbing.* Plate I., fig. 6. 



L. urodus, A. 0. Walker, ' Nat. Hist, of Sokotra,' &c, 1903, p. 220, Plate XIV., fig. 4. 



Various localities round the coast of Ceylon. 



This appears to be a variable species. Most of the specimens examined have a 

 4-jointed appendage to the upper antennas, and, while in one male the 1st gnathopod 

 resembles that of Mr. Stebbing's specimen, in another the hand is conical, with a 

 straight dactylus continuous with the hand. The 1st joint of the 5th perseopods also 

 varies, having the lower margin truncate in some and rounded in other specimens. 



* 'Trans. Linn. Sue.,' Ser. 2, vol. 7, p. 28 : Plate VII., A, 1896. 



