156 SYSTEMATIC ARRANGEMENT 



ff Pillar regularly arched. 



23. Livona. 



Shell subglobose ; axis umbilicated, with a notched callus near the 

 mouth ; aperture circular. Operculum horny. Animal : lateral 

 beards numerous. 



* Shell umbilicated. 



1. L. Pica, t. 41. f. 7. 



** Shell not umbilicated, rarely perforated. Chrysostoma. 



2. L. paradoxa. 



In the British Museum there is a specimen of L. paradoxa, tuber- 

 cular and perforated, nearly like L. Pica. 



c. Shell depressed ; aperture contracted ; whorls cylindrical, more 

 or less separated. Angarina. (Pages 147, 155.) 



24. Angarxjs. 



Shell top-shaped or discoidal, umbilicated ; whorls rounded, scaly 

 or spinal ; aperture circular, entire ; peristome continuous, with a 

 canal on hinder edge. Operculum orbicular, horny. 



1. A.Delphinus, t. 43. f. 4, 5, t. 107. f. 7. 



2. A. niger, t. 107 a. f. 1. 



Kiener (Icon. t. 1. f. I) represents the eyes on short pedicels; the 

 sides of the body not fringed ; the operculum orbicular, horny, of 

 many gradually enlarging whorls. 



25. Vitrinella. 



Shell top-shaped, thin, transparent; whorls circular; axis umbi- 

 licated ; aperture circular ; peristome continuous, thin, simple. Oper- 

 culum horny. 



1. V. valvatoides, Adams, Gen. Moll. t. 49. f. 7. 



The head of Vitrinella divisa is rather long, broad, with horny 

 jaws and a lingual riband. Tentacula long, flattish, and obliquely 

 ciliated. Eyes large, black, lateral, on the basal rounded inflation ; 

 no distinct pedicels. Head-lobes none. Neck-lappets two ; the 

 right narrowish, flat, semiserrated ; the one on pillar side shorter, 

 more oval, and plain. Foot subtruncate, subauriculated in front. 

 Operculigerous lobe plain ; lateral vibracula 3 • 3, obliquely ciliated. 

 Operculum of six or eight spiral turns. — Clark, Moll. 315. 



Operculum of Vitrinella divisa spiral, circular, of many very 

 gradually enlarging whorls. Teeth : central 6 or 8 ; lateral nume- 

 rous, hair-like. 



Tentacles of Vitrinella divisa linear, ciliated. Neck with a lobe 

 on each side, that on the left short and simple, on the right elongate, 



