APPENDIX. 527 



demonstrated that the organs of the two objects are absolutely 

 identical in every point as regards anatomical structure. The 

 variations, except in one point, belong to the shells; the 

 M. brachystom.a is rather more slender, with stronger strise, 

 more gradually taper, a little natter on the top of the volutions, 

 and the animal has the flake-white markings on the foot much 

 more densely distributed than in its hitherto considered con- 

 gener, the M. Ginannianus. But under the circumstances of 

 the identity of the organs of the two, and the quality of the 

 markings being indistinguishable under the microscope, I 

 shall account for the numerical difference of the spots by the 

 ungallant assertion of the schools, that the masculine is more 

 worthy than the feminine ; and as it is well known that in 

 many animals of the same species the colours and markings of 

 the two sexes vary greatly, they may do so here. I have 

 therefore adopted the opinion, that the more slender shell, 

 termed " brachystoma" is the male, and the " Ginannianus }> 

 the female. 



M. Philippics appellations for the so-called species are con- 

 temporaneous ; I therefore propose ' ' brachystoma " for this 

 animal, as being the more significant, receiving the " Ginanni- 

 anus" as its synonym. 



Though the M. nebula has close relations with this animal, 

 I think it distinct. 



MUREX PURPUREUS, Montagu. (P. 499.) 

 Mangelia purpurea, Brit. Moll. iii. p. 465, pi. 113. f. 3, 4, 5. 



We beg that the following notes of this species may be 

 substituted for those quoted. 



Shell. - - The specimen observed presented eight spiral, 

 moderately taper, dark purplish-brown, closely cancellated 

 volutions, of about half an inch in length in the whole, with 

 a narrow white band in the centre of the body -whorl. Ex- 

 amples of larger growth inhabit the coralline zone; these 

 are near an inch long, composed of ten turns, which vary in 

 colour from red-brown to pale drab. At the upper angle of 

 the aperture is a distinct sinus or emargination ; the margin 



