124 JOURNAL OF CONCHOLOGY, VOL. 9, NO. 4, OCTOBER, 1898. 



useful, in dealing with large genera, to group them as much as possible 

 into sections, as Dr. Watson and Mr. Edgar Smith have done in the 

 'Challenger' Reports, and Dr. Jeffreys in the 'Lightning' Report 

 as well as in "British Conchology"; but if the fair meaning of a 

 genus is once over-stepped, there is no finality about it, and every 

 species of Rissoa, Odostomia, or Trochus, on some ground or other, 

 can have a generic name attached to it. 



R. Striatula Mont.— Scilly (Burkill and J.T.M.) ; Killala Bay 

 (Miss Warren) ; Achil Island ; Iona. 



Var. varicosa Marsh. 1 — Occasionally with the type. 

 Var. ecarinata Mtros. (as var. minor-ecarinata?). — New to 

 Britain. Much smaller; spiral ridges equalised in space and not 

 laminated ; labial rib slight or altogether absent. Guernsey ; Scilly ; 

 Land's End. Rare in Britain. At first sight this does not look like 

 R. striatula ; it is but one-fourth the size, and in shape is somewhat 

 like Odostomia dolioliformis. 



R. striatula is a scarce shell everywhere except in the Channel 

 Islands, where it is not uncommon in suitable localities, adhering. to 

 stones deeply embedded in the sand, with R. lactea, Adeorbis, &c. 

 This and the next species have a small operculum for the size of the 

 aperture, and the animal can retire considerably within the shell. A 

 dwarf form is scarce, but is found everywhere with the type. 



R. lactea Mich. — Many parts of Jersey, common (Duprey and 

 J.T.M.); Guernsey and Herm, rare. In 1873 I found several speci- 

 mens in some ballast on the shore at Fowey, in Cornwall; this shell- 

 sand had been brought in a flat-bottomed barge for farm purposes, 

 and, of course, from a short distance, but it may previously have 

 served as ballast from another place. Mr. Alfred Brown has dredged 

 a dead but fresh specimen off the Butt of Lewis, no doubt a "stray," 

 as it is a common ballast shell from Mediterranean ports. 



It cannot now be called "our rarest Rissoa" by any means; it is 

 still rare at Guernsey and Herm, but when searched for in Jersey it 

 may be found in abundance in suitable spots. In one particular part 

 of that island I have taken a score off one stone, and almost every 

 stone in its neighbourhood yielded specimens. It is very variable in 

 sculpture, some examples having twice as many longitudinals and 

 spirals as others. Sowerby's figure is incomplete, as the conspicuous 

 spiral stria? are omitted. 



R. cancellata Da Costa. — Scilly (Smart and others); Eddystone; 

 Torbay; Caldy Island; Milford Haven; Freshwater West; Killala 

 Bay; Birterbury Bay; Iona; the Minch off Barra. 



1 /. Conch., vol. 7, p. 251, 1893. 



2 Nomenclatura, p. 65. 



