29 l'-^5 



Area (Scapharca) dichotoma, Desh. 



(I'l. 11, Kig. :i-i). 

 Area dichotoma, Deshayes, Coiichyl. de l'ile de la Reunion (Bourbon), 1863, p. 22, pi. 3, figs. 18— 19. 



— {liarbdtiit?] dichotoma, Deshaves, Mahtim u. Chemnitz, Concliyl. Cabin., VIII, 2 Abtli., p. 2!), pi. 8, 



ligs. 7 8. 



W. of Koh Chuen, soft clay and mud ('/s). S. of Koh Tuhi, 10 fathoms, clay 

 mixed with sand (',4). Between Koh Kahdat and Koh Kut, 6 fathoms, clay mixed 

 with sand ('2). W. of Koh Kut, HO fathoms, sand and mud ('/2). 



Long. 7 — 17 mm. 



Distribution:— Bourbon (Deshayes). 



Professor Ed. v. Martens, to whom I sent specimens from Koh Kut, has kindly 

 determined these as A. dichotoma, Desh. This species differs, however, in several 

 respects from the specimens from the Gulf of Siam, which have 25 ribs, all of 

 which (except the last two at the anterior end) are divided by a narrow median 

 groove into two ribs of about the same breadth, and covered with regularly-arranged 

 small nodules. As the median groove does not begin quite at the umbo, specimens 

 measuring, for example, about 5 mm. in height scarcely have the ribs at all divided. 

 The interstices between the double ribs are about as broad as the ribs and bear 

 close-set transverse lines. The keel, mentioned by Deshayes, which divides the 

 median part from the posterior end, and which, in his specimens bears four undivided 

 ribs, does not occur in the Siam specimens; whether this is owing to individual 

 or specific character, may be known later; at present I shall name the form from 

 the Gulf of Siam, which we are here considering. Area dichotoma, Desh. var. gratiosa. 



Area (Scapharca) Sabinae, Mori. 



Area Amidanii Sabinic, L. Morlet, Journ. de Conchyl., vol. 37, 1889, p. 189, pi. 8, fig. G. 



— tScapharca) — — Chossk et Fischek, Journ. de Conchyl., vol.37, 1889, p. 292. 



— - — — P. Fischek, Catal. d. Moll, de 1 Indo-Chine, p. 21(j. 



— {Amidaraj — — Mission Pavie Indo Chine, Etudes diverses. 111, 19U4, p. 378, pi. 22, 



fig. 6. 



— iCuncarca) — — Lamy, Journ. de Conchyl., vol.55, 1907, p. 276. 



Coast of Koh Chick (10/2). W. of Koh Kut, 15 fathoms, mud ('/a). Between 

 Koh Kut and Koh Kahdat, 10 fathoms, shells (Ws). Strand of Koh Kahdat ('/a). Phu 

 Quok in the Gulf of Siam (Moklet). 



Long. 9-17 mm. 



Distribution: — Ceylon. — Annam (Cochin China). 



The shells from the Gulf of Siam are rather inequilateral, and not so regularly 

 formed as that figured by Moulet; they agree most closely with the description 

 which Crosse & Fischer give of the individuals from Annam. 



Area (Scapharca) gubernaculum, Reeve. 



Area (jiilternavulnm. Reeve, Proc. Zool. Soc. London, XII, 1844, p. 40. 



— — — Conchol. icon., II, Area. Sp. 14. 



— — — Edg. a. Smith, Lamellibranchiata of the Challenger E.\p.. p. 266. 



