382 MOLLUSCA, 



TuuBiNELLA, Lam., 



Also consists of shells with a straight canal, but without 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 Volutae; they only differ from the latter in 

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

 separates them is not easily traced. The genus 



Stuomhus, Lin. J 



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 



SriiOMiius, Lam. 



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 j^edicles of the tentacula, thicker than the ten- 

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

 jdaced on a thin tail(2). In the 



Pteroceua, Lam. 



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

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

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



In other StromI)i, the sinus of the external margin is contiguous 

 to the canal, forniirig the Rostellauu, Lam. There is usually a 

 second canal ascending the spire, fSrmcd by the external margin 

 and by a coiitinuiuion of the columella. 



(1) Mur. tcolymus, >rartln'i, IV, cxlii, 1.325;— J^/wte pyrum. Martini, III, xcv, 

 916, yi7; — Valuta etramica, List., 829, 51; — Valuta rhinoceros, Chemii., X, 150, f. 

 1407, 1408; — Valuta turhindlus. List., Sll, 20; — Vol. capitellum, List., 810, 19; — 

 Vol. globulus, Cliem., XI, 178, f., 1715; — Vol. turrilu, (im. 



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

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

 ternal margin, there are several repetitions. 



(3) Strombus lambis. Rondel., 79; Martini, III, Ixxxvi, 855; — Sir. chiragru. List., 

 870;— Str. milkpeda. List., 868, 869;— .S7r. scorpius. List., 867- 



