’s RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 203 
ambulatory legs and the penultimate segment of the ab- 
domen, presents two large, oval “tympana”, one at either 
side of the abdomen, similar to, but much larger than those that 
are found in the genus Dotilla. This “tympanum” occurs in all the & 
examined, though it is generally much more conspicuous in dried spe- 
cimens, than in those preserved in alcohol, but it is wholly absent 
in the ©, where the sternites are wholly covered by the very broad, 
semicircular abdomen, the last segment of which is, as usual, deeply 
impacted into the preceding. So far as I am aware, none of my prede- 
cessors have noticed these characteristic “tympana”. Whether they also 
occur in the closely-allied species, Ses. palawanensis Rathbun, Ses. lafondi 
Jacquinot et Lucas and Ses. tetragona Fabricius is not known; of the 
two first named species only Q are still caught. 
113a. Sesarma taeniolata crebrestriata n. subsp. 
Pl. XVI, Fig. 4. 
I have examined some specimens of Ses. taeniolata from Nias, be- 
longing to the Zoological Museum of Amsterdam, that in some respects 
show a distinct deviation from the type. There are altogether 5 specimens, 
- none apparently adult, 4 © and 1 ©, the last one unfortunately without 
chelipeds. Besides, there is from the same locality a young Q of Ses. 
lafondi Jacquinot et Lucas. 
The specimens differ in several more or less mann features from 
the genuine Ses. taeniolata. In the first place the back of the mobile 
finger is much more finely striated transversely, so that 
there are no less than 85—90 transverse and narrow tuber- 
cles, the proximal 50—60 of which are extremely crowded, after which 
they become somewhat broader towards the tip (Pl. XVI, Fig 4). The 
comb-like crest along the upper border of the palm is present also in 
the subspecies, but the prominent transverse crest at the inner surface 
of the palm, so conspicuous even in not yet full-grown © of Ses. tue- 
niolata, is much less developed in crebrestriata: comparing two specimens 
of exactly the same size, one belonging to the type, the other to the 
subspecies, the difference in development of the transverse crest is at 
once noticed. 
The surface of the carapace in the subspecies seemed to me to be much 
more hairy than in the type; the numerous tufts of black hairs are, as 
usual, larger on the anterior half of the carapace, but also the branchial 
regions are beset with numerous small groups, arranged among the sub- 
parallel, oblique lines that are observed here. 
