THE SHORE FAUNA OF CARDIGAN BAY. 109 



Fissurella grseca, Linnseus. One specimen, Aberystwyth. (H. J. F.) 



Acmsea virginea, Miiller. Llanina, near New Quay, one specimen. 

 (C. L. W.) Shells are fairly frequent. (H. J. F.) 



Gibbula magus, Linnaeus. Y-Gamlas, near Pwllheli. (C. L. W.) 



G. cineraria, Linnaeus. Rare. Two living specimens south of Llanrhystyd 

 and tw^o at Gwbert-on-Sea. (C. L. W.) 



G. umbilicata, Montagu. Very abundant in certain areas. (H. J. F. ; 

 C. L. W.) New Quay, Llanrhystyd, north of Towyn, Mochras, near 

 Pwllheli, etc. Considerable differences in form and colouration are 

 observable. The general shell form varies from a dorso-ventrally flat- 

 tened or " Tam-o'-Shanter," to a clumsy rounded turban shape. 

 Li the latter the summit is generally eroded and the penultimate 

 whorl often imbricate and inflated. These differences appear to be 

 due to age. The umbilicus varies between large, open, and deep, and 

 narrow, slit-like, and shallow. These differences appear equally in 

 local examples and in specimens sent from Plymouth, and do not 

 depend entirely upon age and size ; as in several instances the 

 umbilicus was wider and deeper as size increased. The narrowing 

 appears to be due to growth of the adjacent edge of the inner 

 lip, which takes place in some individuals, but not in others. 

 The colour bands may be few and obvious, or numerous and 

 obscure. 



Monodonta crassa, Montfort. Distribution more restricted than the 

 last ; often very abundant and large. (C. L. W.) 



Calliostoma zizyphinus, Linnaeus. One small specimen, Aberystwyth. 

 (C. L. W.) 



Phasianella pullus, Linnaeus. One specimen, on Laminaria, extreme 

 low water, Aberystwyth. (C. L. W.) 



Lacuna divaricata, Fabricius. On Algce, not uncommon. (C. L. W.) 



L. puteolus, Turton. Aberystwyth, one specimen living among Balanus 

 Ijerforatus. (C. L. W.) 



Littorina littorea, Linnaeus. Common almost everywhere. Strongly 

 ribbed when young, ribbings becoming either faint or obsolete after a 

 height of 20 mm. has been attained. (C. L. W.) 



L. neritoides, Linnaeus. Seldom common, but widely distributed. 

 (C. L. W.) 



L. obtusata, Linnaeus. Abundant everywhere, on Fucus. (H. J. F. ; 

 C. L. W.) 



L. rudis, Maton. Abundant almost everywhere. The largest shell so 

 far found in the Bay is from Aberdovey. Total length, 19 mm. ; 



