UNIONID^. 901 



Unio foliaceus, GM., var. pragilis, Nevill, Plate LXXX, fig. 8. 



? Unio foliaeeus, Gld., Proc. Bost. Nat. Hist. Soc. ; Con. Indiea, pi. xlii, fig '6. 



? 0. peguensis, Anth., Am. J. Con., pi. xxv, fig. 2. 



U. fragilis, Nevillj Journ. As. Soc, Bengal, vol. xliv, 1877, p. 89. 



Ten specimens from Yaylaymaw only differ from tlie 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 Bham6 and Shienpagah specimens ; in all of the 

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

 than in Z7. foliaeeus. It is a form extremely close to, if not identical with, the TJ. 

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



Type of var. fragilis from Yaylaymaw ; long 34, lat. Vl\, crass, llj mm. 



Three specimens from Bhamd, 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. foliaeeus, 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, I.e., 

 p. 39. 



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

 rugose anteriorly, especially near the umbones. 

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



Unio bonne audi, E. & S., var. Plate LXXX, figs. 10 & 10 a & 12 & 12 a. 



Unio bonneaiidi, 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 Bham6. 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 & 9a & 96. 



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



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

 bonneaiidi and several other species ; two specimens were also obtained on the Pirst 

 Expedition at Shienpagah. It is next allied to TJ. pacliysoma, Bens., and to some 



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



