mo PA RUE VS I A 



■ Unio favidens Benson, Ann. and Mag., X, 1862, p. 188. — 



Hani.ey and Theoeaed, Conch. Ind., 1876, p. 6, pi. xi, fig. i, 



— Reeve, Conch. Icon., XVI, 1865, P^- xxvi, fig. 131. 

 Margaron fUnio) favidens Lea, Syn., 1870, p. 38. 

 Parrcysia favidens Simpson, Syn., 1900, p. 842. 

 Unio favidens var. marcens Benson, Ann. and Mag., X, 1862, 



p. 188. 

 • Unio marcens PIanley and Theobaed, Conch. Ind., 1876, p. 



19, pi. XLII. figs. 4-6. 



■ Unio smaragdites Benson, Ann. and Mag., X, 1862, p. 190. — 



Hanley and Theohald, Conch. Ind., 1876, p. 5, pi. x, fig. 5. 

 Parreysia smaragdites Preston, Rec. Mus., VII, 1912, p. 299. 



Several varieties, marcens, trigona, deltce, viridula and densa 

 are given by Benson, which hardly seem to me to be worth 

 mentioning. 



Var. tripartita (Lea). 



Possibly worthy of a varietal name. Lea has two shells, one 

 of them the type, in his collection. They are a very little more 

 produced behind the middle than most of the shells of favidens 

 and the epidermis is lighter colored. The nacre is more sil- 

 very and iridescent than in that species. The tripartite lateral 

 of the left valve is a character often found in favidens. 

 Unio tripartifus Lea, Pr. Ac. N. Sci. Phila., VII, 1863, P- 190; 



Jl. Ac. N. Sci. Phila., VI, 1866, p. 57, pi. xix, fig. 55 ; Obs., 



XI, 1867, p. 61, pi. XIX, fig. 55. 

 Margaron (Unio) tripartittis IvEA, Syn., 1870, p. 35. 

 Parreysia favidens (part), Simpson, Syn., 1900, p. 843. 



V^ar. trirostris (Musgrave). 



Shell considerably produced at the anterior end, the central 

 base and the posterior end. The epidermis is brown. Doubt- 

 fully worthy of varietal rank. 

 Unio trirostris Musgrave, Hanley Phot. Conch., 1863, pi. 11, 



fig. 9. — Hanli^y and Theop.ald, Conch. Ind., 1876, p. 6, pi. 



XI, fig. 6. 

 ^Parreysia fazidcns, (part), Simpson, Syn., 1900, p. 842. 



