212 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



of growth ", and may at times be exceedingly reduced or altogether 

 wanting. It would be extremely interesting to know what 

 modification of the mantle margin of the animal it is that gives 

 rise to the formation of these appendiculse at this stage of its growth, 

 and, further, what possible purpose, if any, they serve. 



Mr. Stelfox further points out a more subtile but equally important 

 distinction, viz. that in torquatum the lateral teeth, p. i and p. iii, 

 converge, whereas in swpinum they remain parallel. Tested by these 

 criteria it becomes evident that Mr. Phillips and Mr. Stelfox were 

 right in their conclusions, and that my too great caution was not 

 justified. 



The bibliographic synonymy of torquatum is, therefore, as follows : 



1898. Pisidium parvulum, Clessin : Johansen, Vidensk. Meddel. 



Dansk. Naturh. Foren., Ixvi, pp. 152, 

 159, 160. [Non Clessin.] 

 1913. „ „ Woodward, Cat. Brit. Pisidium, p. 105, 



pis. ii, f. 6 ; iv, f . 8 ; xxvii, f. 3-6. 



„ swpinum, A. Schum. [pars] : ib. pi. xv, f. 9a-/, 



15a-/, 17a-/; xxvi, f. 3a-/. 12a, 6; 



xxvii, f . ] a-f, j-o. 



„ kensloivanum-, Shepp. [pars] : ib. pi. xxvi, f. 13a, b. 



1918. ,, torquatum, n.nov. : Stelfox, Journ of Conch., 



XV, p. 299, pi. viii, f. 14-21. 



Dr. Geyer writes that the species does occur in Clessin's collection 

 mixed with three or four others under the name of P. nvulare, 

 from Anrieder Bach, near Dinkelscherben, Bavaria. He has also 

 lately sent me specimens coming from the River Neckar, at Altbach, 

 near Stuttgart, and reports having it also from the Rhine near 

 Rotterdam, and at Mannheim, as well as from the Bodensee, near 

 Friedrichshafen. Whilst there are specimens from Bohemia in the 

 Clessin Collection. 



The list of occurrences so far as at present known is : — 

 RECENT. 

 England. 



Bedfordshire. — BD. 



R. Ouse, Bromham [C. 0.]. 

 Berkshire. — BE. 



R. Thames, Streatley [C. 0.]. 

 Buckinghamshire. — BX. 



Grand Junction Canal, Cheddington [C. 0.]. 

 „ ,, „ Marsworth [C. 0.]. 



„ ,, „ R. Ouse, Newport Pagnell [C. 0.]. 



Cheshire.— CH. 



Canal, Beeston Castle [CO.]. 

 Herefordshire . — HF . 

 R. Wye, Goodrich [C. 0.]. 



