34 UNIONID^. 



Mollusca ' referred it both to U. tumidus and U. picto- 

 rum, while Moquin-Tandon considered it to be a variety 

 of U. Batavus, It is more strictly a monstrosity^ or 

 abnormal form^ than a variety. 



This species sometimes occurs in company with the 

 next. The Rev. A. M. Norman has recorded in the 

 ' Zoologist' for 1857 having taken specimens at Fleck- 

 ney and Wistow in Leicestershire of the extraordinary 

 dimensions of nearly 4i inches in breadth and more 

 than 2 inches in lengthy the weight being over 3 ounces. 

 Beneath the epidermis the colour of the shell in this and 

 the next species is cream-white. A single individual of 

 U, tumidus has been known to lay 1500 eggs in two or 

 three days. They are deposited in small clusters, each 

 of which contains about 100 eggs. 



2. IT. picto'rum*, Linne. 



Mya pictorum, Linn. Syst. Nat. ed. xii. p. 1112. U. pictorum, F. &H. 

 ii. p. 142, pi. xxxix. f. 1, and (animal) pi. Q. f. 2, 



Body clear red, with a more or less grej^sh tint : mantle 

 bordered with brown ; orifices of the same form and colour as 

 in the last species : foot reddish or yellowish -white, large and 

 tongue-shaped : gills grey : labial palps oval. 



Shell oblong, compressed, not so solid as the last species, 

 glossy, yellow, with narrow zones of brown which denote 

 the marks of growth, transversely wrinkled, with stronger 

 furrows on the posterior side : epidermis rather thin : beaks 

 very httle incurved, and placed at a distance of between one- 

 fourth and one-fifth from the anterior side : umbonal region 

 not so prominent nor so strongly wrinkled as in the preceding 

 species : lumde long and narrow : ligament longer than in U. 

 tumidus : upper margin or hinge-line nearly straight : anterior 

 side rounded : posterior side very gradually sloping and rounded 

 at its extremity, compressed or pinched-up above : lower margin 

 nearly straight : inside cream-white or salmon-colour, highly 

 nacreous : Jiinge not so strong as in the last species ; the teeth 



* Painters'. 



