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



Fseroe Channel, 570 f. ('Triton')! Atlantic off Scilly, 539 — 717 f. 

 ('Porcupine'). 



R. abyssicola Forb. — 18 — 70 f. ; rare in a living state. Isle of 

 Man (L.M.B.C.)! Kyles of Bute, 23^; Loch Linnhe, 24 f.; Arran, 

 29 f., and Lynn of Morven, 40 f. (Knight)! Portincross, Ayrshire 

 (Somerville) ! off Lochranza, 18 — -70 f.; Rum Island, 33f.; off Lesser 

 Cumbrae, 44 f. ; Loch Hourn, 20 — 75L ; Gairloch, 30 f. ; Minch off 

 Barra, 50 f. ; and many other parts of the Hebrides (Somerville 

 and J.T.M.). 



The longitudinal ribs are much more flexuous in some specimens 

 than in others, and the height of the spire is variable. A form with 

 remarkably short spire and tumid body-whorl occurs in the Minch in 

 35 f. ; and a monstrosity from the same district has a second aperture 

 protruding from the original one. 



R. zetlandica Mont. — Scilly, 40 f. (Burkill and J.T.M.); Fresh- 

 water West; Connemara; Killala Bay; Cumbrae, 2of. ; Dornoch 

 Frith; Thurso; Atlantic off Scilly, 69of. (Porcupine). 



Scarce in a living state. This and the next species are the most 

 uniform of all the Rissoce, rarely varying in the slightest degree 

 except in size. I have a dwarf form from Scilly, the Minch, and the 

 Shetlands. A monstrosity from Scilly has a double aperture, similar 

 to the one of R. abyssicola previously noticed. Jeffreys' figure makes 

 this as coarse a shell as R. cancellata, and Sowerby's as still coarser, 

 but the sculpture is in reality finer. 



R. COStata A. Ad. — Under stones at low water mark in the 

 Channel Islands, and in gravelly sand at low water in Torbay, are the 

 only two records I have for the living shell; but dead shells are 

 dredged in many places and at all depths — Iona, 2of. ; Oban, 25f. ; 

 Loch Inver 25f. ; and Loch Linnhe, 4of. (Somerville and J.T.M.); 

 Dornoch Frith; Barra. 



The dwarf is uncommon, from Guernsey, Scilly, and Bantry, and is 

 the var. minor of Monterosato. 



R. parva Da Costa. — Both type and var. interrupta are occasionally 

 milk white. Another form is of the darkest purple, with a white 

 labial rib. Perfectly black specimens are sometimes found in dredg- 

 ings and shore gatherings, but these have either been voided by coal- 

 fish or embedded in black mud. Exceptional specimens of both forms 

 attain C25 inch in length. My largest are from Borough Island, 

 South Devon, both type and var. interrupta, and exceed those from 

 the Shetlands, the next largest. A peculiarity of these Borough 

 Island specimens is that a large proportion of them have a prominent 



\To be conti?iued\. 



