ri;ori:i-:i>i\(;s <n- mi: NATIONAL MI si.i M. 



Genus CHAMBERL.AINIA Simpson, 19OO. 

 (Type, I'nio Imim'sianns Lea.) 



Shell large, very solid in front, thinner behind, round or round obo- 

 vate, without posterior ridge, alate on the post dorsal part when young ; 

 beaks fall, sculpture not seen; surface without sculpture excepting a 

 few slightly pustulous corrugations on the posterior slope; epidermis 

 dull, not rayed; hinge curved; pseudocardinals rather small, stumpy, 

 two in the left valve and one in the right; laterals short, remote, the 

 intervening hinge plate rounded, one lateral in the right valve and two 

 in the left, the upper the smaller, and all curved upward along their 

 inner edges; beak cavities not deep; dorsal muscle scars numerous, 

 deep, extending from the cavity downward and forward; area outside 

 the palleal Hue very wide; nacre lurid bron/y. Animal unknown. 



t CHAMBERLAINIA HAINESIANA Lea'. 



'I'nio haineiantt8 LEA, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 92; * Jl. Ac. N. Sci. 

 Phil., Ill, 1857, ]. 289, pi. xxi, fig. 1 ; *Obs. VI, 1857, p. 9, pi. xxi, fig. 1. 

 vox MAKTENS, Pr. Zool. Soc. Lond., 1860, Pt. 1, p. 15 * SOWERBY, Couch. 

 Icon., XVI, 1866, pi. XLVII, fig. 251.- * MOKEI.ET, Ser. Couch., IV, 1875, p. 

 3i2. *P,ETEL, Conch. Sam., Ill, 1890, p. 154. 

 "Maryaron ( I'nio) Itaineaianux LEA, Syn., 1*70, p. 28. 

 l'ni<> imiH'riali* MORELET, Rev. et Mag. Zool., XIV, 1862, p. 480. 



Siam. 



CHAMBERLAINIA PAVIEI Morelet. 

 * Unto paviti MORKI.KT, .T. de Couch., XXXIX, 1891, p. 241, pi. vn. fig. M. 3 



Siam. 



t CHAMBERLAINIA DUCLERCI Rochebrune. 1 



* I'nio duclerci K'OCIIKBRI'NK, Bull. Soc. Phil., VII, 1882, p. 27, pi. i. fig. 2 (in 

 extract). 



Mekong Kiver, Siam. 



1 The type consists of a single valve- of a young individual. ('. imperialis according 

 to its author attains a size of 142 mm. in height, 192 mm. in length, and 77 mm. in 

 diameter. I have seen a very fine specimen in the Frederick Steams collection 6 

 inches high and 8 in length. It is one of the most magnificent Naiades in the world. 



- Credited by Sowerby to the Little Arkansas River. 



"Very close to C. house!, but more rounded, and having a higher wing. I do not 

 think this can be the same as Morelet's I'nio pairanus, described in Latin in the 

 Journal in 1865, p. 227, and unidentifiable. 



4 It is quite probable that this should form the type of a separate group, but the 

 only specimens I have seen, two badly eroded valves, hardly justify me in separat- 

 ing it. 



