198 A. Alcock —Carcinologieal Fauna of India . [No.’ 2, 
• 
Mensethius monoceros, Miers, Phil. Trans. \ r ol. 168, 1879, p. 485, and Zoology 
‘ Alert,’ pp. 182, 190, 517 and 521, and ‘ Challenger’ Brachyura, p. 37. 
Mensethius monoceros, Haswell, P. L. S., N. 9. Wales, Vol. IV. 1879, p. 437, and 
Cat. Anstr. Crust., p. 9. 
Mensethius monoceros, de Man, Notes Leyden Mus. II. 1880, p, 171, and Archiv. 
f. Naturges. LIII. 1887, i. 219. 
Mensethius monoceros, Richters in Mobius Meeresf. Mauritius, p. 145. 
[Mensethius monoceros, Cano. Boll. Soc. Nat. Napol. III. 1889, p. 175.] 
Mensethius monoceros, Henderson, Trans. Linn. Soc. Zool. (2) V. 1893, p. 843. 
Mensethius monoceros, Ortmann, Zool. Jahrb. Syst., etc., VII. 1893, p. 41. 
Carapace elongate-triangular, most markedly so in the male, the 
lateral epibranchial angles sharp-cut, and the surface very variably 
tuberculated. 
The rostrum, which is flanked on either side by the forwardly- 
directed supra-ocular spine, is styliform, acute, and horizontally com¬ 
pressed, its length being about half that of the carapace in the male, 
but a good deal less in the female. 
The small eyes are imperfectly retractile, and project freely from 
beneath the supra-ocular spine. 
The chelipeds in the male are as long as, or a little longer than, the 
2nd pair of legs, or about equal in length to the carapace and rostrum : 
nre^very much stouter than any of the other legs, and have a 
are considerably shoiuOnd fingers which meet only at the tips, 
good deal shorter than the cat .not stouter than the other legs, and 
through the greater part of their exteiin of legs, which, again, are a 
The 3rd-5th pair of legs are very mfttrum : the fingers meet 
pair: in all the dactyli are strongly recurved 
the posterior margin. than the 2nd 
Very numerous specimens from the Andamans and Nicked along 
Acanthonyx, Latr. 
[Acanthonyx, Latreille, Regne Animal, (2) IV. 58.] 
Acanthonyx, Milne-Edwaras, Hist. Nafc. Crust. I. 342, 
Acanthonyx, A. Milne-Edwards, Miss. Sci. Mex., Crust. I. 142. 
Acanthonyx, Miers, Journ. Linn. Soc., Zool., Vol. XIV. 1879, p. 650; and ‘Chal¬ 
lenger’ Brachyura, p. 42, 
Carapace sub-oblong, rounded behind, and with the dorsal surface 
usually depressed, not markedly constricted behind the prominent antero¬ 
lateral angles, the lateral branchial spines small and not prominent. 
Prae-ocular spine prominent, acute. Spines of the rostrum united at 
the base, acute and but little divergent. Post-abdomen in the male six- 
jointed. Eyes small, mobile, but not completely retractile. Basal an- 
