MARSHALL: ADDITIONS TO "BRITISH CONCHOLOGY." 325 



Jeff., but also to P. tenuicostata M. Sars, though in the latter the 

 sculpture is more flexuous. It was from examples of this decussated 

 form that Brown described his P. reticulahi, and Macgillivray his 

 P. decussata, the latter, however, not being Fusiis decussatus Couth., 

 which is an allied though distinct species, dredged by the 'Lightning' 

 midway between the Hebrides and Faroes in 5oof. and 56of. 



Sowerby's figure is a perfect one of the prevalent British form ; in 

 Jeffreys' the ribs are coarser and the tops of the whorls shouldered, 

 similar to the Greenland and North American form described by him 

 as var. sinithiil^ which is characterised by the whorls being more 

 angulated, and with fewer and stronger longitudinal ribs, though as 

 a matter of fact specimens from all the above localities comprise every 

 degree of sculpture and angularity. Var. sinithii Jeff, somewhat 

 resembles P. exarata Moll., which is a rather critical species, inter- 

 mediate between P. turricula and P. trevelyaiia. llie latter name 

 seems to be in general use, though it is subsequent to P. reticulata 

 Brown (1827). 



The above-mentioned P. ovalis YuqIc^^P. pygmceaYidn\^^P. exigiia 

 Jeff., was dredged by the 'Triton' between the Hebrides and Faroes 

 in 57of., and a single specimen by the Scottish Fishery Commis- 

 sioners off the Butt of Lewis in 545f., (Simpson) ! Gwyn Jeffreys 

 mistakenly describes the whorls as concave instead of convex, his 

 figure has 3A whorls instead of 43-, and the dimensions should be 

 o"2in. by o'l. 



"/*. galerita Phil., a rare Calabrian fossil," has been figured but 

 not described by Jeffreys" as a British species. Sowerby^ says it 

 is not Philippi's species of that name, and figures it as P. icenonim 

 S. Wood, a crag fossil; while Monterosato^ holds it to be P. semicolon 

 S. Wood. However that may be, there are no grounds for considering 

 it a British species beyond the fact that a dead specimen has been 

 dredged "about fifty miles north of the Butt of Lewis." 



Another member of this genus which may be looked for in British 

 seas is P. declivis Lov., which was dredged by the ' Lightning ' off the 

 Butt of Lewis in iSgf , by the ' Porcupine ' off E. Shetlands in 64f., 

 N. Shetlands 345f., and Channel slope 567^ ; by the 'Knight Errant' 

 in the Shetland-Faroe Channel 300-375^ (Jeffreys) ; and by the 

 ' Triton ' in the latter district in 64of. 



P. tenuicostata M. Sars was also dredged by the 'Lightning' in the 

 Shetland-Faroe Channel in 55of.,and by the 'Porcupine' on the Channel 

 slope and in the Atlantic off Ireland in 42of. Another station in 



1 Moll. 'Valorous' Exp., Ann. Mag. N. Hibt., 1877, vol. .vix., p. 332 (sep. copy, printed 

 by error 1876). 



2 Brit. Conch., vol. v., p. 221, pi. cii., fig. 6. 



3 111. Ind. Brit. Shells, p. 16, pi. xxvi., fig. 6. 



4 Nuova Riv. Conch. Med., 1875, p. 42. 



