UNIVALVES. — TURBO. 1 23 



Division IV. — Shell depressed, foliated, spinous or no- 

 dulous, AND umbilicus LARGE, PERVIOUS, 

 AND ARMED WITHIN. 



Delphinus — Dolphin. Exasperatus — Granulated. 



Distortus — Distorted. 



Division V. — Cancellated. 

 Family 1. — Umhilicated. 

 Scalaris — Wentle-trap. 



Family 2. — Imperforated. 

 Principalis — Many-rihhed. Lacteus — Milky. 



Clathrus — Latticed. Pulcher — Beautiful. 



*Clathratulus — Little. Ambiguus — Doubtful. 



Minute Shells. 

 *Elegantissimus — Elegant. *Coniferus — Marginated. 



Simillimus — Similar. *Denticulatus — Toothed. 



*Parvus — Guernsey. *Arcuatus — Margined. 



*Striatulus — Wrinkled. *Striatus — Striated. 



*Reticulatus — Netted. *Costatus — Ribbed. 



*Bryereus — Bryer's. *Unicus — Convej:. 



IndistinctuS — Indistinct. 



Division VI. — Shell with subcylinduical whirls, similar 

 to the last division, but not cancellated. 



Family 1. — Umbilicated. 

 Crenellus — Crenated. Limbatiis — Shouldered. 



*Thennalis — Fresh-water, Carinatus — Keeled. 



Labeo — White-lipp'd. Separatista — Three-keeled. 



Ligatus — Ligature. Niveus — Snowy. 



Foliaceus — Leafy. Helicoides — Brown-ziczag. 



Family 2. — Imperforate. 

 Crenatus — Crenated. Lincinus — Green-and- purple. 



Elegans — Elegant. Lunulatus — Moon-spotted. 



g2 



