CONCHOLOGIA INDICA. 



PLATE XLIII. 

 UNIO. 



1. U. Thwaitesii, Lea, Proc. Philad. Ac. N.S. vol. 1 

 (18.0!)), p. 152; J. Philad. s. 2, vol. 4, pi. 37, 

 f. 125. — lieeve. Conch. Icon. Unio, f. 105. 



Ceylon. 



U. marginalis, Lamarck, Anim. s. Vert. ed. Desh. 

 vol. 6, p. 544. — Hanley, Kec. Bivalves, p. 206, pi. 

 19, f. 53. — U. tesUidinarius, Spengler, Bkriv. Nat. 

 Sclks. vol. 3, pt. 1, p. G5, and U. truncatus, p. 56 

 (fide Miirch). — U. Grajnlandicus (in Lea) from 

 Scliriitcr, Fluss. Conch, p. 181, pi. 9, f. 1. 



AVe describe the hinge of the tj pical form, which is 

 hut little modified in any of the varieties. La the right 

 valve are two sloping anterior teeth, of which the 

 upper and narrower arches more or less downwards, 

 and tlie lower is strong and rather large; the single 

 lateral one is strong, elongated, and bent at the end. 

 Li the left valve, besides the callus, there is one ante- 

 rior and two lateral teeth, the latter scarcely divided 

 until ilir scr, mil iiinii'ly, where they slant down. The 

 ]inn' i|i.il ;ini. rii>r M-:ir is drcidcdly large in proportion 

 to its size ill the allied species. Alin- liui'j oxamina- 

 tion of many scores of examples oi ilii m -t variable 

 species from nearly o\-ery ]);ni of Urii I.nIi liulia. we can 

 only arrive at the conclusion ihat the forms usually 

 dcsii^ii.'ilcd in cabinets, liilinoatus, lamellatus, Corrianus, 

 ^i-.. rnn i 1 1 1 ■ > . mcIi nihci-. We do not assert, how- 

 cvrr, lii.ii ilic sliclls intended by Lea are identical ; for 

 his ligure of bilineatus looks like the young of some 

 broadly-winged Siamese shell (of the Housei type), and 

 ///.•) lamellatus is notable for a peculiarity of deniition. 

 We have delineated some of the more strikinL; tonn-, 



2. U. marginalis, var. typica. — V . marginalis, Ku- 

 cycl. Mclii. Vor.s, pi. 247, f. \. 



Morndabad : Pegu. 



The briel" Lamarckian diagnosis is further dotincd 

 by his reforonco, &c., and his figure. 



.">. U. marginalis, var. obosa. 

 Iviver Irawadi, Hirmah. 



A giant form, wliioh does not exhibit the ochraceous 

 l>!\nd, ami is iieculiarly swollen. It comes between the 

 var. hila, and tho typical form. The upper anterior 

 tooth is almost linear; the lateral are not bent at the 

 extremity, and the tipper one in the loft valve is 

 scarcely developed. 



4. TJ. marginalis, var. Candaharica, Hutton, J. 

 Asi. Soc. Beng. vol. 17. pt. 1 (1849), p. 651. 

 Eiver Sutlej. 



The abnormal characters of shape and colouring are 

 such that Hutton (its discoverer) suggested its possible 

 distinctiveness. The nucleus very closely approaches 

 U. theca, Benson ; the adidt cannot be separated from 

 the form bilineatus. 



5. TJ. marginalis, var. tricolor. — L'. tricolor, Kuster. 

 ed. Chemn. Unio, pi. 45, f. 1 ? 

 A very beautifully painted shell, which is usually 

 more or less compressed. 



PLATE XLIV. 

 UNIO. 



1. U. marginalis, var. cylindrica. 



2. TJ. marginalis, var. zonata. — LT. marginalis, Desh. 

 Encycl. Meth. Vers, vol. 2, p. 587. 



Belgaum, Deecan. 



3. TJ. marginalis, var. bilineata. — U. bilineatus, 

 Keeve (as of Lea), Couch. Icon. Unio, f. 365. 



Nearly all the varieties (especially the immatm-e 

 examples) exhibit two raised lines neiu" the beaks on the 

 umb in il sle]>o. We are aware that Spengler intended 

 to have iiulieatod LT. marginalis as L'. testudiuarius, 

 but his Latin description is most utterly inadequate to 

 define it ; his delphinus. conus, and gibbosus (from the 

 East Indies), must bo ignored for a similar reason. 

 The name Gramlaiuheus yxVc locality was subsequently 

 corrected in the Einloitung, vol. 2, p. G21. by Schroter 

 himself), would mislead. 



4. TJ. marginalis, var. Corriaua. — U, Corrianus, Lea, 

 Trans. Amer. Phil. Soc. vol. 5, p. 177, pi. 9, f. 25, 

 from which llanley, Rec. Bivalves, p. 207, pi. 21, 

 f. 60. 



Near Cjilcutta, vSic. 



This form, always more or less indented in the middle, 

 is sometimes elongated cylindrical, sometimes com- 

 pressed and oval-oblong. The aiixlinal callosity (rarely 

 absent) is more or less developed, and tho anterior or 

 hinge teeth are almost horizontal, curve outward, and 

 are either rather elongated, or if shorter, are rather 

 pi-ominently elevated. 



