MOLLUSCA. SOLENOSTOMATA. 329 



II. Shell turrited; whorls subcorneal, slightly embracing. 



1. BucciNiDiE. Shell truncated or rounded anteally ; the canal 



scarcely produced beyond the anterior margin of the lip, and 

 bent towards the left. 



2. Muricid^;. Shell acuminated at the base ; the canal produced 



beyond the anterior margin of the lip, and either straight or 

 bent. 



3. Cerithiad;e. Aperture of the shell oblique ; canal short, trun- 



cated or recurved. 



4. Strombusid.e. Outer-lip spreading with age, and having a 



notch or sinus near the commencement of the canal for the 

 passage of the head. 



