274 



PSEUDANODONTA ROTHOMAGENSIS Loc. IN BRITAIN. 



By W. II. FOXALL and H. OVERTON. 



Plate 2. 



(Read before the Society, Sept. 13, 1911). 



Following upon the note on this species, forwarded on June 14th, 

 191 1, we have now pleasure in being able to give a more detailed 

 account. 



Specimens of this species were first collected by Mr. Foxall in the 

 River Teme, now a tributary of the Severn, during the August of 

 1905, but owing to their similarity with Ajiodonta cy^ncea they had 

 escaped notice as a distinct species. On recently visiting the locality 

 specimens were again obtained. The nodules on the umbones of these 

 being so prominent at once led to the identification of the species. 



In order to confirm this, a specimen was forwarded to Dr. F. Haas, 

 Frankfurt, for examination, who identified it as being Pseudanodonta 

 rothomagei'sis and similar to those found in the Seine, as described 

 by Locard in 1890 in "Contributions a la Faune Malacologique 

 Fran9aise," .\iv., pp. 12 and 90, and figured in his book "I-es Coquilles 

 des Eaux Douces et Saumatres de France," on p. 219. 



Dr. Haas raises some interesting questions with reference to the 

 distribution of Pseudanodonta, particularly with respect to the rivers 

 and streams in which the species have been found. Since Pseud- 

 anodonta elongata is recorded from the Thames, and Pseudanodo7ita 

 rothoniagensis from the Seine, and now from the Teme, he asks 

 whether the eastern streams possess the former and the western ones 

 the latter, thus raising the question of original drainage and conse- 

 quent stream basins. It will, therefore, be of much interest if ehngata 

 can be found in the Teme, and also rothomagensis in tiie Thames. 



AVe are much indebted to Dr. Haas for so kindly identifying the 

 specimen and raising the interesting point to which we have alluded. 



Clausilia bidentata m. dextrorsum at Skipton. — I am glad to be able to 

 rejDorl the occunence of a dextral Clausilia iiiJeiitata m ih'is district. A specimen 

 was brought to me amongst a number of the normal form by Mr. T. H. Holmes, 

 vvho found them, in April, 1910, on an old moss-covered wall bordering a copse on 

 the Grassiuglon Road, just beyond the inhabited part of Skipton. — C. THEODORli 

 CkI'B'E, {Keaii be/ore the Society, ?>e\^\.. I3lh, 191 1). 



