MONOGRAPH OF THE GENUS 

 HELICINA. 



€har. Gen. MoUuscum terrestre ; testa spirali, sub-globosa ; 

 anfractibus quatuor ad sex ; columella brevi ; aperturae oiargine 

 interno sub recto, margine externo plus minusve incrassato, 

 reflexo. 



Operculo concentrico, semi-lunari vel sub-quadrato, nucleo 

 centrali. 



This genus consists of heliciform land shells, with from four to 

 six whorls, having the inner margin of the aperture nearly 

 straight, and the outer lip generally thickened and more or less 

 reflected. The operculum is concentric, having the nucleus near 

 the centre, and of a semi-lunar or sub-quadrated form. The 

 greater part are brought from the West Indies, many from South 

 America, particularly Brazil, and a few from North America. 

 Several new and interesting species have been lately brought from 

 the Philippine Islands by Mr. Cuming. No species has yet been 

 found in Europe. The species vary in form from the rounded 

 globe to the depressed lens, and the whorls are either rounded or 

 angular in the centre, generally smooth, more rarely ribbed in either 

 direction. The inner lip is sometimes thickened near the colu- 

 mella, which is short, terminating sometimes in an angle, and 

 sometimes in a point, with an incision behind it in the outer lip, 

 and sometimes it is confluent with the outer lip. In attempting 

 to arrange the various species according to their aftinities witli 

 each other, it was found impossible to divide them into sections by 

 any fixed and undeviating rule; in the following arrangement, 

 therefore, we have been content to place together those species 

 which most nearly resemble each other in groups, which may be 

 imperfectly defined in the following manner : — 



Sec. 1. Lip thickened^ sinuous, depressed at the base of the columella. 

 H. Aurantia, Jamaicensis, haemastoma, depressa. Aureola, stria- 

 tula, solidula, Maugerige. 



Sec. 2. Shell thick, sub-angulated ; a notch at the base of the columella. 

 H. Sagra, sub-marginata, pulcherrima, festiva. 



Sec. 3. Shell more globose, thinner, notch deeper. 

 H. major, Brownii, dentigera, hispida, minima. 



