1(54 CEYLON PEARL OYSTER REPORT. 



The eyes are large and globose, not quite reaching the distal end oi the basal joint 

 of the antennular peduncle. The pigment is black. 



The antennular peduncle (fig. 4) is rather long and stoutly built. The basal joint 

 is longer than the remaining two combined. The second joint is quite short and has 

 its outer edge armed with short plumose setre. The third joint is longer than the 

 second. All three joints have a plumose seta on their inner distal corners. 



The antennal peduncle is rather long and slender, with the penultimate joint about 

 three times as long as the terminal one. 



The antennal scale (fig. 4) extends almost to the distal end of the antennular 

 peduncle and is about three times as long as broad. Its outer margin is entire and 

 terminates in a strong spine, beyond which the evenly rounded apex of the scale 

 projects for a little distance. 



The mouth 2^a,rts, in so far as they could be studied in the single available specimen, 

 agreed well with Kossmann's figures. 



The first thoracic limbs (maxillipedes) (fig. 5) are rather short when compared with 

 the same appendage in S. thompsoni. The merus is longer than the carpus, the 

 propodus is small and the nail distinct and longer than the propodus. The whole 

 limb is moderately well armed on its inner edge with short plumose seta?. 



The second thoracic limbs are missing in the specimen. 



The remaining thoracic limbs (fig. 6) are somewhat slender and elongate. The 

 tarsus is about as long as the merus and distinctly two-jointed, the first joint shorter 

 than the second one. The nail is distinct and long, and the whole limb well armed 

 with simple seta?, with a bunch of plumose setae at the basal part of the nail. 



The cxopods of all the thoracic limbs are well developed, and have the outer distal 

 corner of the expanded basal joint slightly acuminate. The flagelliform part is 

 composed of ten joints. 



The pleopods are of the usual type found in the females of this genus. 



The telson (fig. 7) is about one and a half times as long as the last segment of the 

 pleon. It is narrowly linguiform and tapering in shape with a prominent constriction 

 at about one third of its length from the base. The apex is armed with a pair of long 

 spines, between which are a pair of median setse and three small equal-sized spinules. 

 The sides below the constriction are armed with about 28 spines arranged in series 

 of five distally, and three and four proximally. The proximal spine of each series 

 is the shortest, the succeeding spines gradually increasing in length. Above the 

 constriction the lateral margins are armed with three stout spines, longer than the 

 spines arming the distal part of the margins. 



The inner uropod is about one and a sixth times as long as the telson, narrow 

 and having about 45 spines on its inner margin, the spines commencing at the 

 inner posterior corner of the otocyst and extending to the tip. The spines are 

 arranged in series of sometimes two and sometimes three, the most posterior spine 

 nearly as long as the terminal spines of the telson. The otocyst is well developed. 



