54 CEYLON PEAEL OYSTER REPORT. 



produce a useful synoptic table. The following is offered, therefore, with all necessary- 

 reserves : - 



Telsonic segment without lateral notch. 1. S. haswelli, Beddard. 



Telsonic segment with lateral notch 2. 



2- 



First gnathopod with hind margin of wrist 



produced. 2. S. stebbingi, Richardson. 



First gnathopod with hind margin of wrist not 

 produced 3. 



J First antenna, second joint as long as first. 3. S. fractum, Chilton. 



L First antenna, second joint shorter than first 4. 



I Margin of head convex between rostrum and antero- 

 . j lateral angles. 4. S. armatum, Haswell. 



I Margin of head angular between rostrum and 

 [_ antero-lateral angles. 5. S. chiltoni, n. sp. 



In the adult male the first gnathopods strikingly distinguish S. haswelli, 

 S. stebbingi, S. armatum. But in the female of the last-named species these 

 gnathopods do not appear to differ from those of S. fractum, and from those of 

 S. chiltoni only by the greater robustness of the hands. 



Stenetrium chiltoni, n. sp. Plate XII. (A). 



The whole body, dorsally and at the sides, is beset with rather long stiff setae. 

 The head has a rather broad, blunt rostrum not reaching so far forward as the broad 

 epistome. The antero-lateral angles of the head are acutely incurved, and between 

 each of these and the rostrum the margin is produced to a point, thus forming sockets 

 for the first antennae. The segments of the peraeon differ but little in length or 

 breadth ; the sides are nearly straight, with the anterior angles of the first four 

 pointing acutely forwards. The telsonic segment has the lateral margins regularly 

 but quite microscopically serrate, and, as in all the species except S. haswelli, each of 

 these margins far down is produced into a tooth. The indentation or pocket thus 

 formed is followed lower down by a small setiferous indent, to which succeed the 

 rounded corners of the broad apical margin, with its shallow convex projection between 

 the uropods. 



The eyes are narrowly bean-shaped, placed obliquely near the middle of the convex 

 lateral ridges that run below the anterior lobes of the head. 



The first antennae agree closely with those of S. armatum, the second joint being 

 much shorter than the first and not so long as the third ; the flagellum is obscurely 

 six-jointed. The second antennae have the first joint acutely produced on the outer 

 side, but the short second joint and the longer third are not produced on either side. 

 The exopod is conical, having its truncate point tipped with a pencil of setae. 

 Haswell has apparently overlooked the second joint and described the third as 



