HEY : MOLLUSCA OF DERBYSHIRE. 1 1 7 



P. pusillum. — These remarks also refer to this species; they 

 are not very plentiful either. 



P. nitidum. — I find this in the Cromford Canal near the ter- 

 minus to the High Peak Railway ; it is not very common ; 

 also in a small tributary of the Derwent near Ambergate. 



P. roseum. — I have certainly found this in the county, but 

 am uncertain as to locality. 



[I find some difiiculty in recognising species of this 

 order, and during the coming season intend sending speci- 

 mens for verification by the Society's referees]. 



Unio tumidus. — -Yery plentiful in the canals around Derby, 

 but are best secured when the water is off for repairs. 



U. pictorum. — The same remarks apply as for U'. tumidus. I 

 think the Derby to Burton canal is most prolific in thisspecies. 



Anodonta cygnea. — Quite common in the canals close to 

 the town of Derby. 



A. anatina. — Also very plentiful; one day, a short time ago, 

 the water was low in the Derby and Burton Canal, when I 

 took the opportunity to secure about a scuttle-full of the 

 four preceding species. 



Dreissena polymorpha. — Very plentitul where it occurs, 

 but somewhat local. I have found it near Borrowash in 

 the Derby and Nottingham Canal ; near Willington in 

 canal ; near Butterley Ironworks in a large pond. The 

 Midland Railway crosses this pond by means of a pile 

 bridge, the wooden piles of which are covered some inches 

 thick for more than ten feet deep, in fact every piece of 

 timber that is under water is simply smothered with them. 



Neritina fluviatilis. — Somewhat common m the canal at 

 Borrowash; also at Weston. I have found a few specimens 

 nearly black at the mouth of the canal where it enters the 

 River Trent near Sawley. 



Paludina contecta. — Up to the present time I have only 

 met with two specimens of this species in the Derby and 

 Burton Canal, near Willington. 



