UNIO.— Plate LXXXIX. 



Hah. The Euphrates, near Bagdad. 



Quite as much an Anodon as a JJnio : it belongs to 

 the subgenus Pseudodon, of Gould. 



Species 481. (Copied from Lea.) 



Unio E.xiMlus. Un. testd hand magna, teiiiiissimd, valde 

 depressd, intiequilattraU, trigond, antice perangtiKtd, 

 postice dilatatd et alatd, submridi-ltUed, supra cos/am 

 umbonalem trb'adiatd ; margine ventrali retiiso, nali- 

 bus vix eminentibiis, minute wndidatis, margaritd al- 

 bido-ccerulescente ; dentibiis cardiiiaUbm iennibiis, la- 

 mellaribus ; lameUi-s lateraUbus lotigis, subrectin. 



The choice Unio. Shell not large, very thin, much de- 

 pressed, inequilateral, triangular, very naiTow in 

 front, dilated and winged behind, greenish-yellow 

 with three rays beyond the iimbonal ridge ; ventral 

 edge indented, beaks scarcely prominent and minute- 

 ly undulated, nacre bluish-white ; primary teeth thin 

 and lamellar, lateral teeth long and straightish. 



Lea., Journ. Ac. Nat. Sc. Philad. ser. 3. vol. iii. (Obs. on 

 Unio, vol. vi. p. ]4), pi. 25. f. 8. 



Hab. Siara. 



There are numerous small folds both upon the beaks 



and the posterior slope : there is no distinct luinile. In 



the few known examples there are actually three lateral 



laminfe in the left valve, and two in the right. 



Species 483. (Copied from Lea.) 

 Unio tumidulus. Un. testd hand mnynd, satis 



ciild, venfricosd, infequilaterali, oblique oblongu-ellip- 

 tied, postice attenuatd et subangnlatd, teiwbroso-oU- 

 vaced, striata; margine ventrali arciiato, costd umbo- 

 nali subangnlatd, natibus eminentibus minute plicatis, 

 margaritd albd ; dentibus cardiuaUbits lotigis, lamel- 



latis, in valvuld dextrd duobus ; denlibns lateraUbus 

 elongatis, subcnrvatis. 



The little swollen Unio. Shell not large, moderately 

 thickish, ventricose, inequilateral, obliquely oblong- 

 elliptic, tapering and subangular behind, dark olive, 

 striated; ventral edge arched, urabonal ridge sub- 

 angular, beaks prominent and with minute folds, 

 nacre white ; primary teeth long and lamellar, two in 

 each valve: lateral teeth elongated and somewhat 

 curved. 



Le.\, Journ. Ac. Nat. Sc. Philad. ser. 2. vol. iii. (Obs. on 

 Unio, vol. vi. p. 1.5), pi. 35. f. 9. 



Rab. Siam. 



There are three green rays upon the posterior slope. 



Species 483. (Copied from Lea.) 

 Unio fulvus. Un. tesldpurvd, hand crassd, ohlongd (sen 

 anguste ellipticdj, subincnquilaterali, antice compressd, 

 poslici couvexd fuen subventricosdj et subbiangulatd, 

 fnlvd sen luteo-brunned, sublavigaid; costd umbonali 

 roinndatd, natibus prominvUs, margaritd superne pal- 

 lid} rubro-aurantid ; dentibus eardinalibus obliquis, 

 parvis ; lamellis lateraUbus subrectis. 

 The tawny Unio. Shell small, not thick, oblong (or 

 narrowly elliptical), only somewhat inequilateral, com- 

 pressed in front, convex (or subventricose), and sub- 

 biangulated behind, fulvous or yellow-brown, smooth- 

 ish ; umbonal ridge rounded, beaks somewhat pro- 

 jecting, nacre salmon-coloured above ; primary teeth 

 small and oblique; lateral lamellae scarcely curved. 

 Lea, Trans. Amer. Phil. Soc. ser. 3. vol. v. (Obs. on 

 Unio, vol. i.), p. 96. pi. 13. f. 39. 

 U. icier inns, Conrad (teste Lea). 

 Only known to us from Lea's figure and description. 

 Apparently there is a rudimentary lunule ; the primary 

 teeth seem normal, i.e. single in one valve (the right), 

 double in the other. 



