TAYLOR : -MOI.T.USCA OF AUPRUICQ, PAS-DE-CAT. AIS. II3 



Planorbis fontanus Lightfoot. — Two fine specimens, referable 

 to var. alhida Nelson. One so thickly covered with a ferruginous 

 deposit that the whiteness is in great part obscured. Recorded as 

 Planorbis complanafus Drap. by Bouchard-Chantereaux. 



Planorbis vortex (L.). — -Widely distributed and abundant ; 

 shells collected in October from a ditch at Henuin, are very com- 

 pressed, but have a well-marked basal keel ; they are all much encrusted 

 with carbonaceous matter. It also inhabits the canal at Audruicq. 

 Bouchard-Chantereaux records it as very common. 



Planorbis spirorbis (L.) — Found in the pools at Ostove, are 

 very characteristic shells of Planorbis leucostoma Michaud with 

 strongly thickened white rib round the margin of the aperture. 

 Bouchard-Chantereaux records PL leucostoma as very common in the 

 ditches. 



Planorbis carinatus Drap. — A single shell, found during Nov- 

 ember in the canal at Audruicq, and covered by a thick incrustation, 

 a somewhat unusual circumstance with this species. Catalogued by 

 Bouchard-Chantereaux. 



Planorbis marginatus Drap.^ — Widely distributed and abundant, 

 and represented by specimens from St. Pierre, Fort St. Jean, Canal at 

 Audruicq and Polincove. Many of the shells are a large form of var. 

 submarginata, in which the keel instead of being basal is situate more 

 towards its centre, owing chiefly to the increased basal convexity of 

 the last whorl ; these specimens all exhibit a tendency when fully 

 grown to thicken the margins of the aperture. Bouchard-Chantereaux 

 records this as very common. 



Planorbis COrneus (I-).- — Ditch at Henuin and from th.e 

 Audruicq Canal. JNIany of the shells show a tendency to, or belong 

 to the var. bicolor Colbeau, in which the underside is very pale, 

 while the remainder of the shell is normally pigmented ; var. etriiscus 

 Charp. represented by two specimens and characterized by the 

 bulkiness of the whorls ; the var. amnionoceras Westl.=var. microstoma 

 Colb. which has the wliorls flatter and more compressed was also 

 present, but the .bulk of the sliells are not quite mature. It is 

 catalogued by Bouchard-Chantereaux as common in the stagnant 

 waters of Artois. 



Planorbis contortus Drap.— -Widely distributed and very abun- 

 dant, and represented from Polincove, Ostove and the ditches at 

 Henuin. The shells are closely coiled and of good size, the largest 

 being fully six mm. in diameter. Fully adult shells from the pool at 

 Ostove are clearly var. labiata Wesll. in which form a strong white rib 

 encircles the aperture ; specimens in which the mouth is not com- 

 pleted show white transverse bands at irregular intervals, indicating 



