382 



MOLLUSCA. 



^ TuRBiNELLA, Lam., 



Also consists of shells with a straight canal, but yithout varices, dis- 

 tinguishable by the large transverse plicae on their columella, which 

 extend the whole length of the aperture, and which closely approxi- 

 mate them to the conical Volutse; they only differ from the latter in 

 the elongation of their aperture into a sort of canal(l)j the line that 

 separates them is not easily traced. The genus 



Strombus^ Lin., 



Includes those shells with a canal that is either straight or inflected 

 towards the right, of which the external margin of the aperture di- 

 lates with age, but still preserves a sinus near the canal, under 

 which passes the head of the animal, when it extends itself. 



In most of them the sinus is at some distance from the canal. They 

 are subdivided by M. de Lamarck into two subgenera. The 



Strombus, Lara. 



In which the margin expands into a wing of more or less extent, 

 but not digitated. The foot is proportionably small, and the eyes are 

 supported by lateral pedicles of the tentacula, thicker than the ten- 

 tacula themselves. The operculum is horny, long and narrow, and 

 placed on a thin tail(2). In the 



Pterocera, Lam. 



The margin, in the adult, is divided into long a,nd slender digita- 

 tions, varying in number, according to the species. The animal is 

 the same as that of the true Strombus(3). 



In other Strombi, the sinus of the external margin is contiguous 

 to the canal, forming the Rostellaria, Lam. There is usually a 

 second canal ascending the spire, formed by the external margin 

 i^nd by a continuation of the columella. 



(1) Mur. scolymus, Martini, IV, cxlli, 1325; Valuta pyrum, Martini, III, xcv, 

 916, 917; Valuta ceramica, List., 829, 51; Valuta rhinoceras, Chemn., X, 150, f. 

 1407, U08; Valuta turbinellm, List, 811, 20; Fb/. capitellum. List., 810, 19; 

 Vul. globulus, Cheni., XI, 178, f., 1715; Val. turritu, Gm. 



(2) Nearly all the Strombi comprised in the second and third division of Gmelin, 

 observing, that owing to the various degrees of development acquired by the ex- 

 ternal margin, there are several repetitions. 



(3) Strombus lambis. Rondel., 79; Martini, III, Ixxxvi, 555;Str.chiragra,Ust., 

 870; Str. millepeda, List., 868, 869; Sir. scorpius, List., 867. 



