161 
DENTALIUM decussatum. 
TAB. LXX.—Fig. 5. 
Spec. Cuar. Surface marked with twenty or more 
longitudinal stria and several intervening ob- 
scure ones; lines of growth numerous, distinct, 
oblique; mouth elliptical. 
ae 
The longitudinal stria are much more numerous in this 
than in the last, but not much more prominent, although 
the shell is nearly twice the diameter; they are decussated 
by the lines of growth, the obliquity of which seem to 
indicate an elliptic mouth. 
I received this specimen from the great Friend to Botany 
and science, William Borrer, Esq. from Sussex. 
DENTALIUM ellipticum. 
TAB. LXX.—Figs. 6 and 7. 
Spec. Cuar. Nearly straight, quickly tapering, 
rather compressed, surface uneven, aperture 
circular; external edge elliptical. 
ee 
Tue shell being thicker along two sides, gives the tube a 
depressed form, and makes the outer margin of the mouth 
elliptic; the lines of growth give the surface a rugged 
aspect; internally it is beautifully polished: the diameter 
of the mouth is sometimes nearly half an inch. 
This is a large species, apparently not before noticed, for 
want of better specimens; it is however the more aedewinie 
