PLATE III. 



FIG. 



42 Pisidium fontinale v. henslowana (.Sliepp. ) 



— — var. pulchella (Jenyiis) 



— — var. cinerea (Aider) 



— — — var. pallida ((iassies) 



43 — amnicum var. laeviuscula (Moq. ) 



— — — var. flavescens (Moq.) 



44 — milium var. alpestris (Clessiu) 



45 ^ pusillum var. obtusalis (Lamarck) 



— — — var. grandis (Adams) 



46 — nitidum var. splendens (Moq.) 



— — — var. globosa (Adams) 



47 Sphaerium corneum \ ar. pisidioides (Gray) 



— — — var. scaldiana (Normand) 



— — — var. nucleus (Studer) 



— — — var. flavescens (^Macgill) 



48 — lacustre var. ryckholti (Normand) 



— — — var. rotunda (Jeffreys) 



— — — var. brochoniana (Bourg. ) 



— — • — var. ovalis (Ferussac) 



49 — rivicola var. flavescens (Moq.) 



51 Unio pictorum var. curvirostris (Norm.) 



— — — var. latior (Jeffreys) 



— — — vai-. compressa (Jeffreys) 



— — — var. radiata (Moq.) 



— — — var. platyrinchoidea (Dup.) 



52 — tumidus \iir. miilleri (Rossm.) 



— — — var. ovalis (Mont.) 



— — — var. ponderosa (Pascal) 



— — — var. radiata (Colb.) 



53 — margaritifer var. sinuata (Lam.) 



— — — var. roissyi (Mich.) 



54 Anodonta cygnea var. arenaria (Schroter) 



— — — var. rostrata (Rossm.) 



— — — var. stagnalis (Sowerby) 



— — — var. incrassata (Sliepp. ) 



— — — var. radiata (Mliller) 



— — — var. pallida (Jeffreys) 



55 — anatina \ar. ventricosa (C. Pfi-. ) 



— — — var. complanata (Rossm.) 



— — — var. radiata (Jeffreys) 



56 Dreissensia polymorpha v. angusta (Colb. ) 



— — — var. dilatata (Colb.) 



Witli ridge near the beaks. 



Glossy, strongly grooved. 



Larger and flatter. 



More ventricose, with rays from beaks to margin 



Larger, fainter striie. 



Pale yellow all over. 



Very globose, strongly striated. 



Smaller, more tumid. 



Much larger, 5 mm. x 6 mm. 



Larger, lemon coloured. 



Sphajroidal. 



Triangular, striiie coarser. 



Ovate, paler than type. 



Smaller, nearly spherical. 



Pale yellow. 



Small, beaks pi'ominent, shoulders rounded. 



Rounder and flatter. 



Larger and flatter. 



Somewhat oval, with indistinct caliculation. 



Yellow. 



Smaller, shorter, flatter. 



Broader, shorter, yellow-brown. 



Very broad and flat. 



AVith greenish rays. 



With ]>osterior margin produced. 



More oval. 



Wedge-shaped. 



Larger and very solid. 



With greenish or yellowish rays. 



Broader, lower margin incurved. 



Longer, lower margin rounded outwards. 



Broader, upper and lower margins parallel. 



Ovate, crested upper margin. 



Thin, inflated, anterior end rounded, olive-green 



More swollen and solid. 



Streaked yellowish-green. 



Wedge-shaped, light yellow. 



Larger, more solid. 



Oval, compressed, beaks close to the anterior 



margin. 

 With green and yellow rays. 

 Narrower. 

 Broad and Hat, beaks protruding beyond binge 



