30 LITTORINID^E. 



Monstr. Body-whorl spirally and finely but irregularly ridged, 

 the outer lip now and then expanded or contracted above, or 

 a notch formed close to the suture. 



Habitat : Bantry Bay at low water (Barlee) . The 

 variety is tolerably common on Zoster a at Southampton, 

 and abundant among seaweeds in the west of Scotland 

 and east of Shetland, associated with R. parva var. in- 

 terrupta. The monstrosity is sometimes met with in 

 the latter district. The typical form inhabits Bohuslan 

 (Loven), Kiel Bay (Meyer and Mobius) and Christiania- 

 fiord (J. G. J.) ; the variety was found by Professor Sars 

 at Bergen. 



My largest specimens are those from Southampton 

 and Loch Carron, some of them measuring 2 lines in 

 length. A dwarf form, which is much less numerous, 

 may be the male. The spawn-cases are generally solitary, 

 semiglobular, membranous, and light-yellowish-brown ; 

 the fry emerge from a large round hole at the top, which 

 appears when they are developed. 



Mr. Alder was quite right in considering this distinct 

 from R. inconspicua ; but the name [tenuis] which he 

 proposed, being unaccompanied by a published descrip- 

 tion, must cede to one of these which Loven has given. 

 It is thinner and considerably larger than R. incon- 

 spicua, the whorls are more ventricose, the suture is 

 much deeper, and the sculpture very different. It is 

 possible that the present species may have been the R. 

 similis of Brown, which was found by the Bev. William 

 Molesworth at Padstow. 



15. R. membrana'cea *, Adams. 



Turbo membranaeeus, Ad. in Tr. Linn. Soc. v. p. 2, t. i. f. 12, 13. B. 1a- 

 biosa, F. & H. iii. p. 109, pi. lxxvi. f. 5, lxxvii. f. 1-3, and lxxxi. f. 3. 



Body pale-yellow, or slightly tinged with brown : tentacles 



* Membranous. 



