28 tomlin: notes on marine mollusca of north wales. 



whorl that suggests the contour of Troclius granulatus. 

 I have seen specimens of this variety and of the type that 

 were dredged in the Menai Straits, as well as a fine 

 example of the subscalariform monstrosity mentioned by 

 Jeffreys. The var. lyoits'ii Leach has been taken alive at 

 Bull Bay by Mr. Archer. 

 Trochus montacuti Wood. — One dead shell at Dulas Bay 



(F.A.). 

 Lacuna divaricata Fab. — Enormous specimens live on the 

 Laiiiiiiaria beds at Llandudno, which are every now and 

 then laid bare by a low tide round the pier. Both this 

 and Z. pallidula l)aC. are plentiful there, if assiduously 

 searched for; but L. puteolus Turt. is very scarce. The 

 light orange-coloured variety of Z. pallidula is not rare. 

 Rissoa violacea Desm. — Dead at Barmouth. 

 Rissoa costata Ad. — Li Rhyl drift. 



Rissoa semistriata Mtg. — Living at Puffin Island (F.A.). 

 Hydrobia ulvae Penn. — Swarming in myriads on the muddy 

 flats between Mochras and the mainland ; also very large 

 ones near Amlwch. 

 Jeffreysia diaphana Jeff — Very plentiful at Porthwen in 



Anglesea on weeds (F.A.). 

 Skenea planorbis P\ab. — Llandrillo (I'.A). 

 Aclis supranitida Wood. — Several fine specimens from the 

 Dovey estuary. Jeffreys' record of this and Aclis unica 

 Mtg. from Barmouth seems to have escaped Mr. Greene's 

 notice. 

 Purpura lapillus L. — A comparatively gigantic variety lives 

 on mud in the Conway estuary at extremely low tides, 

 while from Llandudno I have three very long narrow 

 shells and several curious monstrosities. The McAndrew 

 Collection (in the Cambridge Museum of Comparative 

 Anatomy) contains a grand series of the genuine var. 

 iiiibriLala l>am., which is frilled almost like the Californian 



J.C., vii., Jiiii , i8y:i. 



