NOTES ON A FEW OF THE LESS-KNOWN 

 BRITISH MARINE MOLLUSCA. 



By GEORGE \V CHASTER, M R.C.S., 

 Soutlifoyt. 



Adeorbis imperspicuus, Monterosato, 

 1S75, Nuova Rivista, p. 36 (name only). 



In the " Conchologist " fur June 24th, 1893, ^ announced the 

 discovery in British waters of this shell which had been identiiied 

 l)y the Rev. Canon Norman as Cyclostrcma millepunctaUim, Friele- 

 Subsequently, when I had an opportunity of examining the 

 description and figures of that species, grave doubts arose in my 

 mind as to the correctness of tlie naming of my shells. These 

 were submitted to Herr Friele who declared that they were not 

 his species, of which he courteously sent a specimen for examina- 

 tion : it is much larger, shaped like Helix pulchclla, and has 

 the sculpture coarser and less regularly arranged in spiral rows. 



The Marcjuis of Monterosato, however, at once recognized 

 my shells as his Adcovhis imperspicuus and kindly sent me a type 

 specimen labelled thus: — " Tornus impeyspicuus Monts = r. subcay- 

 iiiatus, IMtg. pullus ? [Adeorbis) Palermo 80-100 fh." 



The species has, so far as I can ascertain, never been 

 described, except in the "Journal of Conchology " for Jan., 

 1894, ^vhen a short description was given of one of our 

 Oban, specimens (Chaster and Heathcote : jMoII. of Oban, 

 loc. cit.). This, however, partly refers to a varietal modifica- 

 tion, and I, therefore, venture to figure and describe the type. 

 No figure has been published before. 



The Marquis of Monterosato is apparently in doubt as to 

 whether his species is the ky oi Adeorbis siibcariuaiiis, Mtg., or not. 

 When, however, a young shell of the latter, of the same size, is 

 placed beside the former, the two are wholly unlike, evidently 

 having no characters in common, as will be seen by com- 

 paring the rough sketch given in Fig. 2, with Fig. i. 



Adeorbis imperspicuus, Mo?i!;5. Figs, i, la. Shell very thin, 

 spire scarcely raised ; ivhorls about two, flattened and sloping at the 



