MARSHALL: ADDITIONS TO "BRITISH CONCHOLOGY. " 127 



Jeffreys' badly-executed figures of the Rissoce are almost useless for 

 reference. The figures of R. reticulata in 'British Mollusca' are very 

 good, but that of R. calathus is unlike; while Sowerby's uncoloured 

 figures of both forms are perfect in every respect, though nothing 

 but actual specimens can demonstrate the continuity of these two 

 reputed species. 



R. cimicoides Forb. — Scilly Islands (Smart and others) ; Pent- 

 land Frith, 30 f. ; West Orkneys, 45 f. There is no difficulty in deter- 

 mining this shell from the last, as its conical shape is most uniform, 

 although the sculpture sometimes approximates to the last two species. 

 It is a more solid shell, has a thicker labial rib, a smaller and rounder 

 aperture projecting more outwards, the suture throughout is distinctly 

 channelled, and the spire is longer and more attenuated in proportion 

 to the base, giving it a pinched-up appearance. Although as widely 

 diffused, it is not nearly so common as the last. Sowerby's figure of 

 this is identical with his figure of R. calathus; the former should be 

 more conical, and the last whorl larger, as in Jeffreys'. 



Var. minima Jeffr. — East Shetlands. A corresponding form to 

 this prevails in the last three species, which I regard as only variations 

 of the male shell. 



R. Jeffreys! Wall. — Scilly Islands, several dozen specimens 

 (Burkill and J.T.M.). Somewhat variable in shape, size, and 

 sculpture. Anyone who interests himself in the records from the 

 Scilly and Shetland Islands must be struck with the close affinity of 

 the mollusca of these two extremes of the British Isles. 



R. punctura Mont. — Those from Scilly are much coarser than 

 usual, and must not be mistaken for R. jeffreysi, with which this 

 species is found. It is rarely pure white. Specimens from Guernsey 

 exceed a line-and-a-half in length. 



Var. diversa Jeffr. — Scilly 40 f. (Burkill and J.T.M.); Iona, 2of.; 

 Sound of Sleat, 4of. ; and Loch Boisdale, 3of. (Somerville and J.T.M.); 

 Guernsey, 20 f. ; Land's End; Connemara; Killala Bay; Loch Inver 

 25 f. ; Sutherlandshire. 



A slender elongated variety is not uncommon on some of our 

 coasts, and there is also an abbreviated one. The elongated form is 

 the prevalent one in the Crag formation, and is accurately figured 

 by S. Wood. 



The longitudinal strise in the variety are not "finer" but coarser, 

 and often fewer than the spiral striae, with rectangular instead of 

 square spaces. 



R. subsoluta Arad. — New to Britain. 1 Scilly Islands, 40 f.; 



j /. Malacol., vol. 4, pp. 67-8. 



