CONCHOLOGIA INDICA. 
19 
PLATE XLI. 
UNTO. 
See previous plates, ix. to xii. 
1. U. Layardi, Lea, Proc. Ac. Nat. Sc. Philadelph. 
1859, p. 153 : Journ. Ac. Nat. Sc. Philad. ser. 2, 
vol. 4 (and Obser. U. vol. 7), pi. 36, f. 122. — 
Reeve, Conch. Icon. Unio, f. 111. 
Ceylon. 
We are unable to distinguish the exact line of de- 
marcation between this and Thwaitesii ; in charac- 
teristic specimens, however, the front extremity is 
longer and more tapering. 
2. U. involutus, Benson, in Hanley’s Recent Bi- 
valves, p. 385, pi. 23, f. 19. — Reeve, Conch. Icon. 
Unio, f. 177. 
Assam. 
3. U. favidens, var. chrysis, Benson, Ann. Nat. 
Hist. ser. 3, vol. 10 (1862), p. 188. 
River Dojora at Kareily Ghat, near Bareilly. 
4. U. Jenkinsianus, Benson, An. Nat. Hist. ser. 3, 
vol. 10 (1862), p. 185. 
River Berhampooter, Assam. 
The unique type here figured will probably be con- 
sidered an abnormal form of marginalis or Corrianus. 
5. 6. U. Nuttallianus, Lea, Journ. Ac. Nat. Sc. 
Philad. ser. 2, vol. 3, p. 310, pi. 30, f. 25 : Obser. 
U. vol. 6, p. 30, pi. 30, f. 25. 
Assam. 
7. U. consobrinus, Lea, Journ. Ac. Nat. Sc. Philad. 
ser. 2, vol. 4 (and Obser. U. vol. 7), pi. 90, f. 192. 
— Benson, An. Nat. Hist. ser. 3, vol. 10 (1862), 
p. 195. 
Cochin, Malabar. 
Only two specimens, both in the Bensonian collec- 
tion, are known to us. They approach marginalis, of 
which they may possibly prove a tumid variety, yet 
have a fibrous, not a satin-like, style of epidermis, a 
different shape, and a different disposition of colouring, 
the yellow band not being adjacent to the ventral edge. 
There is no appearance, moreover, of the two raised 
lines which adorn the umbonal slope near the beaks, 
which, unfortunately being eroded, do not exhibit any 
marked character. The front extremity is more pro- 
minent and rounded (not obliquely cut off below) than 
in the allied forms. According to Lea the original 
types came from China. 
PLATE XLII. 
UNIO. 
1. U. Birmanus, Blanford, Proc. Zool. Soc. 1869, 
p. 450. 
Bhamo, Upper Birmali. 
2. U. favidens, var. Deltse, Benson, An. Nat. Hist, 
ser. 3, vol. 10 (1862), p. 188. 
River Jellinghy, Upper Gangetic Delta, Ben- 
gal. 
The radiation spoken of consists of almost imper- 
ceptible lines. A specimen from Tirhoot is of an 
uniform dark olivaceous hue. 
3. U. foliaceus, Gould, Proc. Boston Soc. N. II. 
vol. 1, p. 141 : Otia Conch, p. 191. — U. Peguensis, 
Anthony, American J. of Conch, vol. 1 (1865), 
p. 351, pi. 25, f. 2. — Reeve, Conch. Icon. Unio, 
f. 519. 
Tavoy, Birmah ; Pegu. 
Gould’s type (sent to Benson), is unmistakably the 
young of the adult Peguensis. 
4. 5, 6. mareens, Hanley, for U. favidens, var. mar- 
cens of Benson, An. Nat. Hist. ser. 3, vol. 10 (1862), 
p. 188. 
Berhampooter River, Assam. 
The absence of all corrugation is a most important 
characteristic feature. 
7. U. marginalis, var. Anodontina. — U. Anodon- 
tinus, Kuster (not Lamarck), ed. Chemn. Conch. 
Unio, pi. 80, f. 5. 
River Godavery ; Nagpoor ; Sylhet. 
Although we have not fully traced the intervening 
links between this elongated form and the typical mar- 
ginalis, we cannot doubt its approximation to those 
specimens which have been supposed (perhaps erro- 
neously) to represent the U. bilineatus of Lea. Vir- 
ginia is the recorded, and probably the correct, locality 
of the Lamarckian U. Amodontoides, but the types are 
declared to be Indian, not American ; its dentition is 
said to be inconspicuous. In the specimen delineated 
the front teeth are short, strong, and very oblique ; the 
nacre is of a rather pale salmon-colour. 
