MARSHALL: ADDITIONS TO "BRITISH CONCHOLOGY." 303 



'the specimen ascribed by Canon Grainger to this species, from the 

 Belfast deposit, is not this but P. brachystoma ; I have seen the shell. 

 A very small and slender variety comes from Achil Island. P. costata 

 has a closer affinity to P. striolata than to P. attenuata, and Gwyn 

 Jeffreys must have been thinking of the former when he wrote that 

 "the spiral striae are closer and finer" than in P. attenuata, for in this 

 species the spiral striae can always be seen with a lens, while P. 

 attenuata is apparently smooth, and requires a microscope to detect 

 the spiral sculpture. His description errs in other respects, while the 

 dimensions, as well as his figure, appertain to the var. coarctata. 

 Nearly all the published figures are most unsatisfactory. Forbes and 

 Hanley give three (pi. cxiv. a), of which their fig. 3 is a slender form 

 of the type called by old writers var. metcalfei, their fig. 4 is not 

 applicable to any form of our shell, being too large and broad, while 

 their fig. 5 is a good delineation of var. coarctata, but by an oversight 

 of the artist no dimensions are attached. Sowerby also gives three 

 (pi. xix.), of which figure 21 is not this species at all, but P. bertratidi 

 Payr., a Mediterranean species; fig. 22 is a back view of a narrow 

 form, and the dimensions should be reduced one-half; though fig. 23 

 is a good one of var. coarctata, and leaves nothing to be desired. 

 Captain Brown's figures, though poorly executed, give the best idea of 

 the typical form.^ His Fusus pyraniidatus, on the other hand, is the 

 intermediate form of this species, and not a variety of P. nebula as 

 cited by Forbes and Hanley, Brown's dimensions of " three-eighths 

 inch by one inch " being an obvious error for fin. by ^in.^ 



P. rugulosa Phil. — Birterbuy Bay (Walpole); Scilly Islands, two 

 immature specimens ; St. Ives and Hayle in Cornwall ; Achil Island. 

 Very few examples of this species have been found on our coasts, and 

 these are usually rolled or water-worn out of all resemblance to the 

 rugulose Mediterranean specimens. Those from Ireland differ in no 

 respect from the Scilly and Land's End examples ; but it is an ex- 

 tremely variable shell, and there are numerous foreign named varieties 

 of it. 



P. brachystoma Phil— Scilly Islands 4of., Fowey i6f, Babba- 

 combe Bay and Teignmouth, fine ; Milford Haven, Southport, 

 Connemara, Arran 25f., Sound of Sleat 4of. Fossil in the Belfast 

 deposit (Grainger) ! 



Var. alba Marsh, n. var. — Shell white. Dredged off the Mull of 

 Cantire in 2 7f In shape and sculpture P. brachystoma comes very 

 close to some of the dwarf forms of P. nebula, but the apical whorls 

 differ materially. 



I Brown's III. Rec. Conch., p. 6, pi. v., figs. 45, 46. 

 z Loc. cit., figs. 19, 20. 



