438 SPECIES OF THE SYSTEMA. 
such a sequence is frequent with the smaller specimens I hold 
the circumstance deserving of record. Since that shell pre- 
cisely, and alone of those present exactly, answers to the 
definition, and the presence of cornewm in the collection is 
asserted, the identification can scarcely be doubted. The 
species differs from the typical white entalis, as our author 
has observed, in being of a dirty horn-colour, and much more 
often interrupted in growth; the specimens are opaque, and 
have the past strictures at the stages of increase conspicuously 
evident. The only other shells in the collection that at all 
approach the described features are some worn examples of 
D. Tarentinum, which Linneus manifestly confused with the 
preceding species. 
Dentaliuw politunr and eburwernr. 
The Dentalium eburneum of Deshayes (Mon. Dent. pl. 8, f. 8), 
and the D. politwm, as figured by Mawe (Lin. Conch.) and Crouch 
(Introd. Lam. Conch.), but with the rings more manifest, are 
present in the Linnean cabinet, as declared by Linnzeus, and 
exclusively, but conversely, suit the descriptions of these 
species: for, strange to relate, naturalists have not remarked 
the wide distinction between the raised rings (“annulis” or 
“striis convexis”’), which are stated to distinguish the latter, 
and the simple or incised annular striz, which characterise the 
former. 
Gualtier’s figure (the one next G, for there are two F's), what- 
ever it may have been meant for, and I doubt if it were intended 
for politum proper, exhibits, nevertheless, the peculiar aspect of 
the ringed strize, and is therefore illustrative. 
Mentaltuin ncrwuetine, 
The cited figure in Plancus was so rudely executed that it is 
difficult, if not impossible, to decide what species was intended 
by it: in the ‘Museum Ulrice’ it was referred to entalis, and 
looks, indeed, not unlike a fragment of Tarentinum. The Den- 
talium gadus of British writers has been plausibly suggested as 
