EDITORIAL NOTES. 127 



Scarcity of live material has proved an almost insuperable barrier to the study 

 of the radula of the Mitrid<c, and one heartily welcomes Dr. Cooke's paper on 

 this subject in Proc. Zool. Soc, 1919, p. 405. The Gwatkin collection has fur- 

 nished him with fourteen species of Vexillnin, and thirty-seven belonging to ten 

 other groups, into which he divides the rest of the family. With reference to the 

 generic name Cyliitdromiira, we may note that Dall, in United States Nat. Mm. 

 Bull. 90, p. 52, has named Pterygia niicella Bolten (= Valuta dactyhis L. ) as the 

 type of Bolten's genus Pterygia, of which therefore Cylindroviitra becomes a 

 synonym. 



Vitrea and Pyramidula Destroyed by Ants. — Whilst on a visit to Burnley 

 during 1919, I spent some time in the woods, near the River Brun, searching for 

 moUusca. They were very scantily represented, and were mostly found under 

 large stones. Many of these stones cover the nests of the Red Ant, and in and 

 around these nests were many dead shells, very few indeed being found under the 

 stones not occupied by the ants. From this it would seem that the molluscs 

 when seeking shelter had trespassed upon the ants' domain with fatal results.— 

 A. K. Lawson [Read before the Society, February nth, 1920). 



LoligfO vulgaris Lam. in British Waters. — Mr. W. E. Hoyle in this 

 Journal, vol. 10, p. 200, suggests that this species may occur in British waters, as 

 well as /.. forbesi Steenstrup. In some material I obtained recently for dissection 

 from Plymouth Marine Biological Station, I was fortunate to find male and female 

 examples of this species obtained in the neighbourhood of Plymouth. The dis- 

 tinction that one notes first, is the much darker coloration of L. vulgaris ; on 

 closer examination the entirely different arrangement of the suckers on the long 

 tentacles is the best criterion ; and in many minor points the species are different. 

 — R. WiNCKWORTH {Read before the Society, May 12th, 1920). 



Occurrence of Physa gyrina Say in Great Britain. —The occurrence of 

 Physa gyritta Say, at Cardiff, has been confirmed by Mr. Bryant Walker, of 

 Detroit, Michigan. The shells were first found in the summer of 1918, by Master 

 Paul W. Richards, in a small pond situated in one of the numerous flat meadows 

 which lie to the west of Cardiff". The pond in question is fed by a natural spring, 

 the water draining off through a connecting ditch, which is linked up with other 

 cross ditches beyond. The whole district is on the alluvium, and is artificially 

 drained. An allied species, Physa heterostropha Say, flourishes in the vicinity. 

 Physa gyrina Say, which is a well-known species in North America, is larger, and 

 and has a more elongate spire than is usual with Physa heterostropha Say. Further 

 than that the surface of the shell is dull instead of glossy, except in the case of the 

 young shell ; the striation is irregular, and the surface of the shell often malleated. 

 The animal has long filiform tentacles, and the characteristically digitate mantle. 

 — J. Davy Dean {Read before the Society, February nth, 1920). 



