Il6 JOURNAL OF CONCHOLOGY, VOL. l6, NO. 4, AUGUST, I92O. 



but present no unusual features. Bouchard-Chantereaux catalogues 

 V. spirorbis, V. planorbis and V. minuta. 



Sphaerium corneum (L.). — ^Widely distributed and very common. 

 Specimens gathered in ISovember from the ditch at Henuin are of a 

 greyish-yellow colour, the var. flavescens of Macgillivray. The speci- 

 mens from Ostove are remarkably globose and almost spherical, the 

 var. nucleus Studer ; there are also many representatives of the var. 

 vittata Gamier, which is distinguished by three or four concentric 

 zones of yellow and the darker ground colour of the shell, as well as 

 a few of the var. regularis Pascal, which has a distinct yellow area 

 around the margin of each valve. The Audruicq Canal yielded 

 examples of the var. cinerea, in which the whole shell is of a cinereous 

 or ashy-grey, and also from another part of its course some pretty 

 examples of var. vittata Gamier. This species is catalogued b.y 

 Bouchard-Chantereaux. 



Sphaerium rivicola (Leach) is locally common in the Audruicq 

 Canal. Many of the shells are uniformly ash-grey, var. cinerea, 

 but others belong the var. litnbata, in which the margins of the valves 

 are zoned with yellow, and there is a black concentric zone near the 

 middle of the shell. Bouchard-Chantereaux cites Cyclas rivalis Drap. 

 which Moq. includes as a var. oi S. corneum, but Boucliard-Chantereaux 

 probably alludes to this species. 



Sphaerium lacustre (Miill.) — A small and not perfectly mature 

 shell found in July at Polincove. This is listed as Cyclas calyculata 

 Drap. by Bouchard-Chantereaux. 



Pisidium amnicum (Milll.) is represented by specimens of var. 

 7iitida Baudon, a form which is almost devoid of the well-marked 

 concentric ridges of the type shell. They were collected in July at 

 Polincove. This is cited as Cyclas palustris by Bouchard-Chantereaux. 



Pisidium pusillum (Gmelin) was found in the pools of Ostove. 

 Bouchard-Chantereaux cites Cyclas fontinalis Drap. which, according 

 to Moquin-Tandon, refers in a large measure to the present species. 



Pisidium henslowanum Jenyns.— >0f this species there is a pale 

 but unusually fine specimen (five mm. diameter) collected during July 

 in the canal at Audruicq. This is another addition to the fauna of 

 the Pas-de-Calais. 



Unio pictorum (L.).— In the canal at Audruicq, and represented 

 by an almost uniformly yellowish variety, the var. flavescens Moquin- 

 Tandon and by tlie var. milleti Moq., which is characterized by its 

 greenish-yellow colour, and the distinct and regular darker growth 

 periods. The form of this variety is well represented, though in a 

 smaller size, by Dr. Jeffreys in Brjt. Conch. . Bouchard-Chantereaux 



