CONCHOLOGY. 
The tube without internal chambers or partitions, 
1. Dentalium, Shell free, tubular, regular, slightly 
eurved, tapering to the hinder extremity, and 
open at both ends. 
In this genus are included the Dentalium 
Entalis, D. dentalis, D. striatum, D. gadus, 
2. Cecalium, Shell resembling the last, except 
that it is closed at the lower or smaller extremity. 
including the Dentalium trachea, D. imper- 
foratum, D. glabrum, and the Vermiculum 
incurvatum of Mont. 
3. Serpula, Shell wholly or partially attached, 
circular’ or more or less undulately elongated, 
slightly tapering, solitary or in groups. Including 
the whole of the genus Serpula. 
The tube separated into cells by internal partitions, 
This division includes all those very minute 
shells which have hitherto been arranged under 
the genus Nautilus, 
CLASS 11.—CIRRIPEDES, 
Body inclosed in a tunic, and furnished on the 
upper part with many jointed feet in two rows, and 
each of these feet bearing setaceous fringed cirri in 
pairs seated on a pedicel. 
4. Coronula, Shell fixed, suborbicular, rather 
