7356 Molhslcs. 



This shell differs from that of P. fonlinalis in its larger size, its 

 form, the great development of the body-whorl, the shortness of the 

 spire and the contour of the outer lip. Only two examples were pro- 

 cured, and one of these is imperfect. The examination of the animal 

 must decide whether the claims of the shell to specific distinction are 

 well grounded or not. The following circumstance leads me to think 

 that the animal will be found to differ from that of P. fontinalis : — 

 In the case of those Mollusca that have the mantle so developed as 

 to enwrap the shell, the surface of the shell is highly polished and 

 free from extraneous coating ; Physa foutinalis, the Amphipeplese, the 

 Cypreae and the Marginellae may be taken as examples. On the 

 other hand, the shell of Physa acuta, which we have seen has very 

 short digitations of the mantle, is commonly more or less clothed 

 with confervoid growth. Now, the shell of the doubtful Physa is coated 

 with a calcareous earthy deposit, and that green Conferva so com- 

 mon to fresh-water shells. I am therefore led to infer that the animal 

 differs from that of P. fontinalis in having the mantle-margin and its 

 processes but little if at all developed. 



The footpath from Oxford to West Hincksey, after passing the 

 railway pond and railway, is bounded on either side by a ditch, in 

 which the water-lilies {Nymphcea alba and Nuphar lulea) grow. The 

 ditch on the right was the habitat of the above-described shell. If 

 any reader of this paper should have the opportunity of searching 

 for, and succeed in finding, this Physa, I should feel greatly obliged 

 if he would favour me with living specimens. They should be 

 wrapped ir^ a little duckweed to keep them moist, and forwarded in a 

 wooden box by post. 



Alfred Merle Norman. 

 Sedgefield, Durham, 



January 6, 1861. 



The Firth of Clyde Mollusca : Errata. — The reader is requested to malte the fol- 

 lowing corrections, with a pen, in the last pnrt nf llic ' !Mollusca of the Firth of Clyde.' 

 P. 7238, line 4 from bottom, and p. 7239, line 3, for Gowrock read Gourock ; p. 7238, 

 line 3 from bottom, for Lamillaria read Lamelliiria ; p. 7239, line 14, for Allan read 

 Arran ; p. 7241, line 5 from bottom, p. 7247, line 9, and p. 7248, line 4, for Philene 

 read Pbiline; p. 7240, line 7, for sepangnbiris read septangularis ; p. 7240, line 10, 

 for Ptilidium read Pilidiuni ; p. 7240, line 19, for Lefroyi read Leiifroyi; p. 7242, line 

 32, for Man read Arran ; p. 7245, line 3, for rustica read oculata ; p. 7247, line 12, 

 for Amouroncium read Amouroucium. — Alfred Merle Norman ; January 5, 18G1. 



