224 TEREBRINyE. 



tacles or wanting. Mantle enclosed, with an elongated 

 siphon. Foot small. 



Operculum annular, nucleus apical. 



Shell dense, solid, turreted ; aperture with an oblique 

 notch in front j outer lip thin, not variced. 



Sub-fam. TEREBRIN^. 

 Operculum ovate, pointed, with nucleus apical. 



Genus ACUS, Humphrey. 



Eyes on the tips of the tentacles. 



Shell subulate, whorls numerous, simple ; aperture elon- 

 gate, emarginate anteriorly, not produced into a canal ; 

 columella simple, incurved, not tortuous ; outer lip simple, 

 acute, without a sinus at the fore part. 



Syti. • Subula, Schum. Terebraria, Rqfin. Turricula, 

 Hermans. 



Ex. A. maculata, LiniKBus, pi. 24, fig. 1. Operculum, 

 A. crenulata, Lamarck^ fig. 1, a, 1, h. Shell, A. macu- 

 lata, fig. 1, c. 



In this genus the tentacles are very short, with the eyes 

 at their tips. 



Species of Acus. 



albida, Gra?/. duplicata, Linn 



cajrulescens, Lam. Dusumieri, Kien. 



casta, Hinds. eburnea, Hinds. 



chlorata, Lam. fatua, Hinds. 



cingulata, Kien. hastata, Gmel. 



crenulata, Lam. laurina. Hinds. 



dimidiata, Linn. maculata, Linn. 



