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5. Carapace granulate, with a broad, longitudinal , median 



groove, extending backward to the intestinal region. 

 Palm of cheliped at outer and inner surface with a longi- 

 tudinal piliferous line, close to the under margin of the 

 palm and continued on both surfaces of the immobile 

 finger; a similar line is observed at both surfaces of the 



dactylus. Tympana on the legs very large D. brevitarsis de Man x ) 



Carapace finely punctate, not granulate; the longitudinal 

 median groove extends only to the gastric region. Palm 

 of cheliped without longitudinal piliferous lines, neither 

 are there any on the fingers; only the dactylus has two 

 crests. Tympana on the legs indistinct; carpo-propodite 

 and dactylus densely tomentose D. profliga Nobili J ) 



6. Nearly the whole outer surface of the merus of the external 



maxillipeds occupied by a convoluted sulcus, in such a 

 way that the elevated parts of the surface constitute a 

 W-shaped figure. Surface of carapace grooved, the sulci 

 constituting roughly a five-rayed star, the anterior ray 

 directed forward on to the front, the antero-lateral rays 

 passing on to the external orbital angles, the posterior 



rays directed obliquely-backward and triple D. sulcata Forskal s ) 



Convoluted groove at outer surface of merus of external 

 maxillipeds confined to lateral part of this surface ... 7 



7. A large quadrangular tooth in the middle of the inner margin 



of each finger of the chela D. clepsydrodactylus Alcock 4 ) 



Fingers of chela without large. teeth 8 



8. A transverse groove on the carapace, close and parallel to 



the posterior border , . . . 9 



No transverse groove on the carapace ; the latter strongly 

 areolated, cardial and intestinal region circular, undivided 

 by a longitudinal sulcus, quite smooth and non-granular. 

 Last pair of legs without tympana on the dorsal surface 

 of the meropodites D. malabarica Nobili 5 ) 



9. Merus of external maxillipeds about twice as large as ischium, 



granular. Fingers of chela not very much longer than palm 10 



1) Journ. Linn. Soc. London, v. 22, iSSS, p. 130, pi. 9, f. 1 — 3. Alcock, 1. c. p. 367. It occurs in the Mergui Archipelago. 



2) Boll. Mus. Torino, t. 18, n°447, 1903, p. 22. Some specimens were found in fresh water in the Upper Sadong River (Borneo). 



3) Literature: Nobili, Ann. Sc. Nat. (9) t. 4, 1906, p. 315. The autor is inclined to unite this vvell-known species of the Red 

 Sea with D. affinis Alcock (1. c. p. 365, 111. Zool. "Investigator", Crust. pit 10, 1902, pi. 63, f. 1) for the differences enumerated by Alcock 

 do not prove to be constant in examining a large material. Laurie (Journ. Linn. Soc. London, v. 31, n° 209, 191 5, p. 46S — 469) likewise 

 supports Nobili's opinion in an even more elaborate way. 



4) L.c. p. 367, 111. Zool. Mnvestigator", Crust. pit 10, 1902. pi. 63, f. 2. Found on the shore of the Mahanaddi Delta. 



5) Boll. Mus. Torino, t. lS, n° 452, 1903, p. 20, f. 6. Common at Mahè (Seychelles). 



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