238 ZOOLOGISCHE MEDEDEELINGEN — DEEL III. 


9 Sides of carapace straight, not convexly arched. 10 
Sides of carapace rather regularly convexly arched; greatest breadth 
of carapace considerably more than length. Front high, perpendicularly 
curved; anterior margin regularly convex in Q, if viewed from above, 
in o with very slight emargination. Postfrontal lobes rounded off, 
not sharp anteriorly. Inner surface of palm of cheliped with prominent, 
curved crest, consisting of 10—11 granules. — Ses. obtusifrons Dana. 
10 Upper border of mobile finger of cheliped with 2—3 longitudinal 
rows of very small tubercles. Japanese species, living on rocks below 
high-water mark, exposed to the surf; breadth of carapace about 
20 mm. Ses. rupicola Stimpson. 
Upper border of mobile finger of cheliped smooth or provided at 
most with very small tubercles, irregularly disposed. Species living on 
banks near brackish water; breadth of carapace exceeding 25mm. 11 
11 Carapace nearly quadrate, length nearly equal to distance between 
external orbital angles; sides slightly divergent posteriorly. Anterior 
margin of front deeply emarginate. Ses. dehaani H.Milne-Edwards '). 
Carapace longer, length distinctly less than distance between external 
orbital angles; sides convergent posteriorly. Anterior margin of 
front with a shallow and indistinct emargination. Ses. neglecta de Man. 
12 Upper margin of palm with a distinct, horny-coloured, granulate crest. 
Mobile finger of cheliped furnished with 13—15 obtuse, spiniform 
tubercles. Ses. eydouxt H. Milne-Edwards. 
Upper margin of palm without a continuous granulate crest. Mobile 
finger of cheliped with 8—9 acute tubercles. Ses. granosimana Miers. 
2. Sesarma 8.8. 
(Ses. pentagona Hutton is not included in this key, on account of its 
being quite insufficiently known. 
1 Distance between external orbital angles more than or equal 
to (in rare cases even slightly less than) the length of the carapace 
in the median line. 2 

1) Ses. obesa Dana is evidently nearly related to this species, but it is much smaller 
(length of carapaee 6 mm., breadth 6.75 mm.), the palm seems to be very high, and the length 
of the movable finger equals the height of the palm; the walking legs are much less hairy than 
those of Ses. dehaani, 
