360 MEMOIRS OF THE CARNEGIE MUSEUM. 



EXPLANATION OF PLATE IX. 



All figures are three-fourths natural size, a, lateral view; b, dorsal view. 



Fig. 1. Lasmigona (Platynaias) viridis (Rafinesque). Gravid specimen, about 

 full-grown, from Conneaut Outlet, Conneautlake, Crawford Co., Pennsylvania, collected 

 May 14, 1908; C. M. Cat. No. 61.3297. 



Fig. 2. Lasmigona (Patynaias) viridis (Rafinesque). Gravid specimen, young. 

 This specimen shows the great similarity of young L. viridis to L. suhviridis (compare 

 Fig. 4). From Conneaut Outlet, Conneautlake, Crawford Co., Pennsylvania, collected 

 August 7, 1908; C. M. Cat. No. 61.3679. 



Fig. 3. Lasmigona (Platynaias) suhviridis (Conrad). Gravid specimen, about 

 full-grown, with exceptionally solid shell, from water heavily charged with lime. From 

 Conococheague Creek, Greencastle, Franklin Co., Pennsylvania, collected September 6, 

 1909; C. M. Cat. No. 61.4222. 



Fig. 4. Lasmigona {Platynaias) suhviridis (Conrad). Gravid specimen of the 

 normal, thin-shelled form, from Schuylkill Canal, Manayunk, Philadelphia Co., Penn- 

 sylvania, collected April 24, 1909; C. M. Cat. No. 61.4219. 



Fig. 5. Lasmigona {Lasmigona) costata (Rafinesque). Gravid female of typical 

 shape, from Shenango River, Shenango, Mercer Co., Pennsylvania, collected September 

 27, 1909; C. M. Cat. No. 61.4235. 



Fig. 6. Lasmigona {Lasmigona) costata eriganensis Grier. Specimen from the 

 set of types. From Lake Erie, Presque Isle Bay, Erie, Erie Co., Pennsylvania, collected 

 May 22, 1909; C. M. Cat. No. 61.4223. 



Fig. 7. Lasmigona {Pterosyna) complanata (Barnes). Gravid female, not quite 

 full-grown, from Leboeuf Creek, Waterford, Erie Co., Pennsylvania, collected September 

 14, 1909; C. M. Cat. No. 61.4238. 



