184 JOURNAL OF CONCHOl.OGY, VOL. 13, No. 6, Al'RIL, I91I. 



have only three. Var. jadertiniim Brus. is more peculiarly three- 

 rowed. My largest types are five-eighths-of-an-inch in length, and the 

 smallest one-eighth-of-an-inch ; the latter resemble C. pusillwn Jeffr., 

 but have a different apex. The large type-form lives under stones 

 and in seaweeds between tide-marks, while the smaller and more 

 slender one is common in the coralline zone. An extreme form is 

 cylindrical, and does not exceed one-third-of-a-line in width, while 

 another has the outlines of Cerithiopsis tuhercularis. The sea-shore 

 at Falmouth consists largely of this species, and the finest specimens 

 come from Helford River in Falmouth Bay, and Milford Haven. 

 Jeffreys' figure has the spire too attenuated ; that figure more nearly 

 represents the form called by Continental writers \ax.Jadertinuin Brus., 

 which is not uncommon on some of our coasts. Forbes and Hanley 

 figure the type well, together with the next variety. 



var. simplex Jeffr. — The peculiar ornamentation of this variety 

 is not always well defined. The shell is smaller than the type, does 

 not exceed ten whorls, and is limited to Guernsey and its islets. 



var. lactescens Jeffr. — Weymouth (Damon) ! Guernsey, Scilly, 

 Tenby, Killala Bay, and Bundoran. A rare variety. 



Cerithium proceriim Jeffr. has been dredged by the 'Lightning' 60 

 miles off the Butt of Lewis in 500 fathoms, and also by the 'Triton ' 

 between the Hebrides and Faroes. 



C. tiiberculatmn L. = C. vulgatiiin Bruguiere is in the same category 

 as Bulla striata Bruguiere, both species having been found in a rolled 

 condition on different parts of the Jersey coast. Gwyn Jeffreys gives 

 a good figure in his Supplementary Plates, of which Sowerby's is a 

 copy, though these figures represent, not the type, but a specimen of 

 the var. ahicastnim Brocc. 



Triforis perversa L. — This is nowhere common on our coasts in 

 a living state. In South Devon it usually appears in rock-pools at 

 very low water, and more rarely as a parasite on compound ascidians, 

 with Cerithiopsis tuhercularis 



var. pallescens Jeffr. — Scilly Islands (Burkill and J.T.M.); 

 Channel Islands, Eddystone, and Torbay. Some of the Scilly speci- 

 mens are pure white. 



No British specimens attain the size of those from the Mediter- 

 ranean, for which sole reason the latter is held by some writers 

 to be the type shell, and a distinct species from the British one, 

 T. adversa Mont. Guernsey produces our largest examples, half-an- 

 inch in length, and Scilly the smallest, one-eighth-of-an-inch, while 

 those from the Mediterranean range from one-tenth to a full inch in 

 length. Immature shells are pyramidal and keeled at the base. A 

 small and slender form from Scilly has a deeply-incised suture and a 



