180 BR J. Or. DF, MATSr ON THE PODOPHTHALMOUS 



closely that of the other species, that it is scarcely possible to 

 distinguish between them. The principal characters by which 

 it differs from the other species are found in the anterior legs 

 and more especially in the hands. 



In S. livida the fingers are comparatively shorter in propor- 

 tion to the palm, the latter being more developed. The pro- 

 portion of the horizontal length of the fingers to that of the 

 palm, measured at the lower margin, is in 8. livida as 10 : 11, 

 in S. guttata as 10 : 9g, in 8. HaswelU as 10 : 9, in S. hidens 

 and in S. Bussumieri as 10 : 8. In Sesarma livida the im- 

 mobile finger is thus shorter than the length of the lower margin 

 of the palm ; in the four other species the latter is shorter than 

 the immobile finger. 



The anterior margin of the arm presents a strong, -simple, 

 acute, and triangular tooth ; and the upper margin of the immobile 

 finger is covered with a longitudinal row of 10-11 low and some- 

 what scalariform prominences. As regards the form of the male 

 abdomen, S. livida completely agrees with ;S^. hidens. 



The Mergui specimens agree very well, in the form of the 

 cephalo thorax and the shape of the male abdomen, with the 

 adult typical specimen of S. livida in the Paris Museum, The 

 leo-s, however, are slightly different. Thus the spine of the 

 anterior margin of the arm has a somewhat different form from 

 the New-Caledonian type, in which the anterior (distal) margin 

 of the spine malvcs a rather obtuse angle with the distal part of 

 the anterior margin of the arm, lying beyond the spine, whereas 

 in the Mergui examples the angle so formed is nearly a right 

 angle, as in 8. hidens. The fingers are shorter than the palm, the 

 above-defined proportion being as 10 : 12. The upper margin of 

 the mobile finger presents only seven slightly prominent eleva- 

 tions, which seem to have a different structure from those of the 

 New- Caledonian type specimen. The outer surface of the im- 

 mobile finger is also a little more flattened than in the latter, 

 and the meropodites of the ambulatory legs aro somewhat 

 more enlarged. Perhaps a careful examination of adult specimens 

 of the Mergui species wiU prove it to be distinct from the 

 New-Caledonian 8esarma livida. 



Dimensions of the largest specimen : — 



millim. 



Distance between the extraorbit?il teeth 16f 



Length of the cephalofchorax 13 



