272 CEYLON PEAEL OYSTEE REPORT. 



( >f the above characters the least valuable Is that of the 3rd pleon segment, as the 

 number and position of the teeth vary considerably. 



Maera rubro-maculata (Stimpson). Plate V., fig. 30. 



Gammavus nibro-inaculatus, Stimpson, 'Proc. Acad. Nat. Sci.,' Philadelphia, 1855. 



ffi. rubro-maculata (Stimpson), '"Challenger" Amphipoda,' p. 100s, Plates XCV., XCVI. 



Ceradocus rubro-maculatus (Stimpson), Della Vai.i.e, 'Gamm. d. Golfo di Napoli,' p. 720. 



From Kodramallai Point south ward to Galle. 



Length of adult male 10 millims. 



In the specimen dissected, the mandibular palp was set far back, the 1st joint 

 produced forward in a sharp point ; the '2nd widened abruptly near the base, then 

 narrowing gradually (fig. 30. m.). 



Maera tenella (Dana). Plate V., figs. 31. 



Gainmarus tenellus, Dana, ' U.S. Explor. Expn.,' p. 952, Plate 65, fig. 7. 



Mara tenella, Sr. Bate, 'Cat. Amph. Crust. Brit. Mus.,' p. 193, Pkte XXXV., p. 3. 



Cheval Paar, 10th November, 1902. One male, length 6 millims. 



Head about as long as the first 2 segments. Eye nearly round, rather small. 



Mesosome and pleon without dorsal teeth ; epimere of the 3rd pleon segment with 

 6 or 7 unequal teeth on the hind margin, the posterior angle acute and somewhat 

 upturned (fig. 31. pi. 3 ). First segment of the urus with 3 small postero-dorsal teeth 

 and a dorsal depression ; 2nd segment with 1 tooth. 



Upper antennae reaching to the end of the pleon; 1st joint twice as thick and 

 nearly as long as the 2nd ; .'3rd very short ; flagellum rather shorter than the first 



2 joints of the peduncle, 13-jointed; appendage 8-jointed, two-thirds of the length of 

 the flagellum. 



Lower antennas scarcely reaching beyond the end of the peduncle of the upper; 

 the flagellum about as long as the 3rd joint. 



Both upper and lower antenna? are sparsely setose, except the flagellum of the lower, 

 which is more hairy. 



First gnathopods : side-plates small, produced in front to an acute angle ; wrist 

 longer than the hand, the hind margin densely setose ; hand with the palm ill-defined, 

 and transverse rows of setae on the hind margin (fig. 31. gn. 1 ). 



Second gnathopods: side-plates small, quadrate, with rounded angles; 1st joint 

 stout, two-thirds of the length of the hand and nearly twice as long as the next 



3 joints together ; wrist transverse ; hand large, widening distally ; hind margin as 

 long as the front, straight, with a few setae, and ending in a strong curved tooth 

 which defines the palm ; this is transverse, convex, uneven, and spinulose (fig. 31. 

 gn.*). 



First and 2nd peraeopods slender, slightly longer than the 1st gnathopods ; 1st joint 



