222 BRITISH MOLLUSKS. 



Hab. Throughout Europe. Siberia. North Africa. England, chiefly 

 southern and eastern parts. (In gently flowing rivers, canals, and ponds.) 



The Painters' Unio, so called from its shell having been used by 

 painters of the last century for holding their colours, is more plenti- 

 fully and much more widely diffused than the preceding species. 

 U. tumidus is confined to Northern and Central Europe. IT. pic- 

 torum ranges in a southerly direction to Sicily and North Africa, 

 and northwards to Finland, passing over Siberia. In Britain, both 

 species are confined to England, chiefly the southern and eastern 

 parts, but reach sparingly to the south of Yorkshire. Neither of 

 them appear in Scotland or Ireland. Mr. Jeffreys remarks that 

 " the shells are still to be had of any artists'-colour-man in this 

 country, containing a preparation of ground gold and silver leaf, 

 for illuminating work." 



The shell of U. pictorum may be readily recognized by its straight 

 elongately oblong form, fulvous tone of colour, devoid of rays and 

 concentric epidermic ridges. The umboes in this species are only 

 slightly wrinkled, and the hinge teeth are not so prominent as in 

 the preceding. Forbes and Hanley notice " a somewhat tortuous 

 variety taken in the River Lea, near London, and in the northern 

 districts of England, with the rostrum bending below the level of 

 the incurved ventral margin, and with the hinder side either greatly 

 produced or with its upper edge arcuated. In this form the pri- 

 mary teeth are apt to become rudimentary." 



M. Moquin-Tandon divides this species into two, characterizing 

 seventeen varieties of it, as follows: — (J. Sequienii ; 1, shell nearly 

 straight below ; 2, shell nearly straight, cardinal teeth stronger ; 

 3, shell large, nearly straight, of a bright green colour; 4, shell 

 smaller, paler, slightly dilated behind ; 5, shell slightly sinuous 

 below ; 6, shell elongated, sinuous below, arcuated behind ; 7, shell 

 elongated, sinuous below, a little dilated behind ; 8, shell elongated, 

 very sinuous and very arcuated. C. pietorum ; 1, shell yellow, 

 with green rays ; 2, shell yellow, without rays ; 3, shell larger, 

 yellow or brownish, with dark bands ; 4, shell rather elongated, 

 lanceolate behind ; 5, shell longer, rather narrowed posteriorly ; 

 6, shell very large, more elongated, rather narrowed at the poste- 

 rior extremity, ventricose, thick, brown ; 7, shell more elongated, 

 much narrowed behind, olive-brown ; 8, shell more oval, rather 

 truncated posteriorly, very dark brown ; 9, shell smaller, shortened, 

 a little arched, wedge-shaped posteriorly, olive. 



