CARCINOLOGICAL STUDIES. 103 



when looking at fig. 7 of Plate XII of my Report on 

 the Crustacea of the Mergui Archipelago, that the pecti- 

 nate ridges have the same oblique direction in Ses. Melissa 

 and in Ses. erythrodactijla , but I am quite unable to re- 

 solve this question. 



The upper surface of the palm in our new form appears 

 a little more granular, than in Ses. êrytlirodactijla ^ the 

 granules being arranged mostly in oblique lines, which 

 run from the pectinate ridges to the proximal margin 

 of the upper surface. The outer surface of the palm is 

 minutely granular, like in Ses. erythrodactijla ; these granules 

 are more crowded towards the base of the immobile finger 

 and gradually appear arranged in oblique lines towards 

 the rounded under margin. The proximal half of 

 the outer surface of the immobile finger is 

 flattened and distinctly separated from the 

 under margin of the finger by a longitudinal 

 ridge; the distal end of the finger is, however, convex 

 and rounded. In Ses. erythrodactyla the whole outer sur- 

 face of the index appears convex , smooth and rounded , 

 and does not present the described longitudinal ridge. 



The upper margin of the dactylus bears a row of 20 — 

 21 transverse prominences, which have exactly the same 

 structure as in Ses. erythrodactyla; they are namely scala- 

 riform, the proximal part of each prominence being de- 

 pressed , minutely and longitudinally striated, and larger than 

 the obliquely descendiug distal part. According to my de- 

 scription of Ses. Melissa, the anterior distal declivity of the 

 transverse prominences should be larger in this species than 

 the posterior or proximal one, but I have afterwards ob- 

 served (Zoolog. Jahrbücher, Bd. IV, 1889 p. 435) that this 

 description perhaps may be incorrect. The upper surface of 

 the mobile finger is somewhat granular at the base, but the 

 rest of its outer surface is smooth. The inner surface of the 

 palm is somewhat granular and provided with a short, 

 but prominent granulated transverse crest, 

 composed of six or seven granules. This crest is the prin- 



Notes from tlie Leyden ]yiu.seu.m, "Vol. ^XJII. 



