1S96.] A. Alcock — Carcinologieal Fauna of India. 265 



87. Arcania septemspinosa, (Fabr.), Leach, Edw. 



Cancer septemspinosns, Fabr., Mant. Ins. I. 325, and Bnt. Syst., II. 463 : Herbst, 

 Krabben, I. ii. 259, pi. xx. fig. 112. 



Leucosia septemspinosa, Fabr., Ent. Syst. Suppl., p. 351 : Bosc, Hist. Nat. Crust. 

 I. 237 : Latreille, Hist. Nat. Crust, et Ins. VI. 119. 



Iphis septemspinosa, Leach, Zool. Miscell. III. p. 25 : Desmarest, Consid. Gen. 

 Crust., p. 170 : Milne Edwards in Cuvier Regne Animal, Crust., pi. xxv. fig. 4, and 

 Hist. Nat. Crust. II. 139: Bell, Trans. Linn. Soc. Vol. XXI. 1855, p. 311, and Cat. 

 Leucos. Brit. Mus. p. 22 : Stimpson, Proc. Ac. Nat. Sci. Philad. 1858, p. 161 : Miers, 

 Ann. Mag. Nat. Hist. (5) V. 1880, p. 317: Sluiter, Tijdscbr. Nederl. Ind. XL. 

 1881, p. 159, fig. 1. 



Arcania septemspinosa, Miers, ' Challenger ' Brachyura, p. 300 : Henderson, 

 Trans. Linn. Soc. Zool. (2) V. 1893, p. 403. 



Carapace bluntly rhomboidal, the anterior blunt angle of the rhomb 

 forming the elegantly bilobular, slightly projecting, front, and the lateral 

 and posterior angles being all produced to form huge slightly-curved 

 spines — the lateral ones being the longest. Besides these, there are 

 four other smaller spines in the posterior part of the carapace, namely 

 one on either side at the level of, and one on either side below, the large 

 posterior spine. The surface of the carapace is finely granular in irreg- 

 ular patches, the granules being most distinct on the large spines. 

 The hepatic regions are separated from the branchial regions on either 

 side by a transverse crease or pucker, but otherwise the regions of the 

 carapace are not clearly demarcated. The summit of the (antero- 

 lateral) convexity of the hepatic region is, usually, faintly acuminate. 

 The chelipeds are symmetrical and slender, and are more than twice the 

 length of the carapace (posterior spine excluded) in both sexes : the 

 long cylindrical arms are very finely and uniformly granular : the 

 almost filiform fingers are a little longer than the slender tapering hand. 

 The true legs are slender and smooth, and the dactyli are thickly fringed 

 with rather long hair : the first pair exceed the arm in length by their 

 dactylus and rather more than half their propodite. 



Colours streaky and patchy red. 



The carapace of an average adult of either sex is about 20 millim. 

 long, and about 20 millim. broad. 



Localities : Andamans, Arakan, Gangetic and Mahanaddi Deltas, 

 Madras coast, Persian Grulf. It is commonest on muddy bottoms at 

 about 25 fathoms. 



Of 92 specimens in the Indian Museum the lateral spines are found 

 to vary a good deal in length : they are usually, in adults, about as 

 long as the arm, and sometimes a good deal longer ; but iu the young 

 they are usually much shorter than the arm. 

 J. ir. 34 



