MONOCEROS.— Plate I. 



The short-toothed Monoceeos. Shell ovate, thick, 

 spire short, somewhat acuminated, transversely im- 

 pressly striated, encircled with three obsolete noduled 

 ribs ; ashy blackish, encircled vrith white spots, aper- 

 ture white. 



Gray, Wood's Index Test. Supp. pi. 4. f. 10. 



Purjmra cornigera, De Blainville. 



Testa junior. Purpura ocellata, Kiener. 

 Hab. Xipixapi and Monte Christi, West Columbia (in 



crevices of rocks at low water) ; Cuming. 

 The tooth, though perfectly developed, is rather minute 

 in this species. 



