MARSHALL: ADDITIONS TO 'BRITISH CONCHOLOGY.' 383 



The above changes do not, however, put matters 

 quite straight, for PhiHppi described his shell as ' much 

 smaller ' and as ' having spiral striae,' while Monterosato 

 calls our shell ' pin grandeJ As regards size, however, 

 Mediterranean specimens are much smaller than British 

 ones, both species attaining on our coast 2\ lines in length; 

 but the question of ' spiral striae ' is rather puzzling. I 

 should have attributed this to O. terebellum, but that that 

 is also one of Philippi's species. Or Philippi may have 

 had O. terebellum and O pusilliim mixed, as I have had 

 myself from Continental collectors ; they are certainly very 

 much alike. But, at any rate, Philippi's 'spiral striae' is 

 not present in any British form in this section. 



The true O. pusilla is intermediate between O. lactea 

 and O. innovata. While O. lactea is a lengthened cone, 

 O. pusilla is subcylindric, and O. innovata tubular. In 

 O. lactea the ribs are curved, in O. pusilla they are oblique, 

 and in O. imiovata they are flexuous, especially on the 

 lower whorls. The characters of O. innovata are well 

 defined in 'British Conchology,' while O. pusilla differs 

 from it in being thinner, the sculpture is finer and closer, 

 the spire is gracefully proportioned, and there is no tiace 

 of a tooth. Both forms have their peculiar variations, 

 and they are especially variable in size. 



The localities given by Jeffreys in 'British Conchology' 

 must not now be relied upon, as he included both species ; 

 but I think it will generally be found that, except from 

 Guernsey, nearly all the shells under this name in British 

 collections are O. pusilla Phil, (non Jeff.). I append below 

 the localities that I can vouch for myself. 

 O. pusilla Phil, (non Jeff.). The sculpture varies in the degree 

 of obliquity, being occasionally nearly straight, but it is 

 never curved as in O. lactea, nor flexuous as in O. innovata. 

 It attains the same length as the latter in Britain, but is 



