UNIONIDiE. 901 



TJnio foliaceus, Gld., var. feagilis, Nevill. Plate LXXX, fig. 8. 



? Unio foliaceus, Gld., Proc. Bost. Nat. Hist. Soc. ; Con. Indica, pi. xlii, fig. 3. 



/ (J. peguensis, Anth., Am. J. Con., pi. xxv, fig. 2. 



U. fragilis, Nevill, Journ. As. Soc, Bengal, vol. xliv, 1877, p. 39. 



Ten specimens from Yaylaymaw only differ from the Pegu form, in that the 

 epidermis, except on the posterior angle, is quite smooth ; unfortunately they all 

 seem young shells ; the two biggest are exceptionally tumid, in this respect differing 

 from the others, as also from the Bhamo and Shienpagah specimens ; in all of the 

 above the nacre is less yellow-tinged towards the umbones, and the teeth thinner 

 than in U. foliaceus. It is a form extremely close to, if not identical with, the TI. 

 comptus, Desh,^ stated by MM. Crosse and Pischer to be the 77. sumatrensis of Lea. 



Type of var. fragilis from Yaylaymaw; long 34, lat. 17J, crass. 11| mm. 



Three specimens from Bhamo, all young ; long. max. 43, lat. 24, crass. 13 mm. 



Thirty specimens from Shienpagah, all young ; long. max. 32, lat. 17, crass. 

 9J mm. 



Specimens of TI. foliaceus, from Pegu ; long. 58, lat. 22, crass. 17 mm. 



Unio pugio, Bens. 



Unio pugio, Bens., Ann. and Mag. Nat. Hist., 1862, p. 193; Con. Indica, pi. x, fig. 1 ; Nevill, /. c, 

 p. 39. 



Abundant at Myadoung, Bham6, and Yaylaymaw. Very young specimens are 

 rugose anteriorly, especially near the umbones. 

 Long. 57, lat. 27, crass. 20 mm. 



Unio bonneaudi, E. & S., var. Plate LXXX, figs. 10 & 10a & 12 & 12^^. 



Unio bonneaudi, Eyd. & Soul., Mag. de Zool., 1838, pi. ; Con. Indica, pi. x, fig. 6, and pi. xlvi, 

 figs. 5, 6 ; Nevill, I. c, p. 39. 



Very abundant at Myadoung, Irawady, second defile, Shuaygoomyo, Yaylaymaw, 

 and Bhamd. It varies considerably in being more or less rugose in sculpture. 

 Long. max. 52, lat. max. 29, crass. 24 mm. 



Unio andersonianus, Nevill. Plate LXXX, figs. 9 & 9<^ & 96. 



Unio andersoniana, Nevill, Jouni. As. Soc., Bengal, vol. xlvi, 1877, p. 40. 



This species was found at Myadoung in tolerable abundance, together with TI. 

 bonneaudi and several other species ; two specimens were also obtained on the First 

 Expedition at Shienpagah. It is next alHed to TI. pacliysoma, Bens., and to some 



' Nouv. Archives, x, pi. vi, figs. 3, 4. 



