242 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
Pl. CCLXXII. Fig. 5. 
ANCILLARIA MARGINATA, Lamarck, Anim. sans vert., vol. vii. p. 413. 
Encyclopédie Méthodique, pl. 393. f.2.a,6. Sowerby, Species Con- 
chyliorum, Part I. f. 40 to 43. 
Pl. CCLXXII. Fig. 6. 
ANCILLARIA RUBIGINOSA, Swainson, Journ. of Science, vol. xviii. p. 283. 
Zoological Illustrations, 2nd series. Sowerby, Species Conchyliorum, 
Part I. f. 49 to 52. 
Pl. CCLXXII. Fig. 8. 
ANCILLARIA CASTANEA, Sowerby, Species Conchyliorum, Part I. f. 20 
to 23. 
Ancillaria ventricosa, var., Swainson. 
OLIVA, Bruguiére. 
Testa polita, oblonga, subcylindrica, basi emarginata ; spira brevi, apice 
acuto, anfractibus confertim volutis, suturis plus minusve canali- 
culatis ; apertura perangusta, prope ad apicem extensd; columella 
sulcato-striata, subtumida, sepé oblique contorta; labro externo, 
simplici, interdum crassiusculo. 
The Olive have been associated together by all writers since the time 
of Gualtieri, with the exception of Linneus. The great author of the 
‘Systema Nature’ was so struck with the close approximation of the 
species of this genus to each other, that he referred the whole of them 
under one common title to his genus Voluta; supposing the columellar 
sulci to be analogous to the plaits upon which he founded that division. 
There is no genus throughout the system that may be said to offer so 
many obstacles to the proper determination of the species as that which 
we have now under consideration ; they run so completely the one into 
the other, whether in regard to form, or distribution of colour, that few 
naturalists have ventured to make a particular study of them. The latest 
