NO. 1205. SYNOPSIS OF THE NAIADES— SIMPSON. 655 



* Hemilastena dehiseens Agassiz, Arch, flir Nat., 1, 1852, p. .50. 



* Maryaron (Margaritana) dehiseens Lea, Syn., 1852, p. 43; 1870, p. 69. 

 "Baphia dehiseens H. aud A. Adams, Gen. Rec. Moll., II, 1857, p. 499. 



* Margaritana dehiseens Clessin, Conch. Cab. Ano., 1873, p. 274, pi. xxiv, figs. 



3, 4. — *B. H.Wright, Check List, 1888.— * P.etel, Conch. Sam., Ill, 1890, 

 p. 173. 

 *Anodonta dehiseens P^tel, Conch. Sam., Ill, 1890, p. 178. 



* + Unio oriens Lea, Tr. Am. Phil. Soc, IV, 1834, p. 73, pi. vi, fig. 5 ; Obs., I, 1834, p. 



83, pi. VI, fig. 5.—" Chenu, 111. Conch., 1858, pi. xiv, figs. 2, 2a, 2b.— Kuster, 

 Conch. Cab., 1861, p. 222, pi. lxxv, fig. 2.—* Sowerby, Conch. Icon., XVI, 

 1868, pi. LXiii, fig. 314. 



* Unio hildrethi Delessert, Eec. Coq. Lam., 1841, pi. xix, figs, 4a, 46. 



Ohio, Cumberland, and Tennessee river systems. 



Genus SOLENAIA Conrad, 1868. 

 (Type, My octopus emarginaius Lea.) 

 Solenaia Conrad, Am. .11. Conch., IV, 1869, p. 249. 



Shell greatly elongated, falcate, rather thin, narrower and rounded 

 in front, the upper anterior portion being strongly sulcate, gaping at 

 anterior base and behind, having a strong posterior ridge that ends in 

 a point at the post base ; beaks low ; sculpture of slightly double-looped 

 concentric ridges; epidermis rayless; hinge line narrow; teeth rudi- 

 mentary, being mere vestiges of one or more lamellar laterals in each 

 valve; dorsal scars numerous, in a line under the hinge; anterior scars 

 faint; posterior elongated; palleal line with a distinct posterior sinus. 



According to Fischer the foot is enormously developed for the purpose 

 of burrowing, as in Mycetopoda. It is probable that the mantle is closed 

 behind into two siphons. 



(Group of Solenaia emarginata.) 



Anterior region much narrowed, drawn out in the direction of the 

 anterior base, marked oft" from the rest of the shell by a faint ridge. 



t SOLENAIA EMARGINATA Lea. 



^Mycetojms emarginatus Lea, Pr. Ac. N. Sci. Phila., IV, 1860, p. 308; *.J1. Ac. N. 

 Sci. Phila., V, 1863, p. 398, pL l, fig. 305; * Obs., X, 1863, p. 34, pi. i,, fig. 

 305.— Sowerby, Conch. Icon., XVI, 1868, pi. ii, fig. 6.— 'Fischer, Jl. de 

 Conch., XXXVIII, 1890, p. 11.—* P.etel, Conch. Sam., Ill, 1890, p. 186. 



*Plaiiris (Mycetojms) emarginatus Lea. 



*Anodonta emarginatus Clessin, Conch. Cab. Ano., 1875, p. 169, pi. lv, figs. 5, 6. 



''Mycetopus (Solenaia) emarginatus Fischer^ Bull. Soc. d'Autun, IV, 1891, p. 135. 



Siam. 



