55 



Genus 1. TEREBRA, Brugmere. 



Animal ; disc short, very thick and muscular ; head proboscis- 

 shaped, cylindrical, tentacles short and conical with an eye 

 situated on the outer side of each at the base; respiratory 

 siphon cylindrical, rather prolonged. 



Shell; elongated, turriculated, sinuated at the base ; whorls very 

 numerous, but slightly convex, apeoc very sharp and elevated ; 

 aperture small ; columella swollen, contorted, terminating in a 

 point ; lip simple. Operculum horny, imhricated. 



The genus Terehra is one of those well-defined groups which cannot 

 easily be confounded with any other ; it is distinguished by a long subulate 

 shell, composed of a number of small whorls tapering gradually to a point, 

 as sharp as a needle, and the base of the aperture is invariably sinuated. 

 The shell of Turritella has very much the form of Terehra, but the aperture 

 is rounded and entire ; so that Terehra may be Hkened to a very long 

 drawn-out Bucc'mmn, and Turritella to a similarly elongated Turho. The 

 shells of these genera may, however, be readily distinguished from each 

 other without referring to the generic pecuharities of the aperture. The 

 calcifying function of the animal is much the more vigorously exercised 

 in the genus under consideration, the shell is more soKd, it exliibits a 

 greater variety of structural embellislunent, and whilst the colours are vivid 

 and less obscure, they display a more pleasing variety of pattern and design. 



The soft parts of Terehra are naturally very lunited, the head and tenta- 

 cles are small, and the entire mass when fully exserted, rarely extends 

 beyond a tenth of the shell. But although the animal is cumbered with a 

 shell ten times the length of its exserted body, it is not of the sluggish 

 character of the Mitre ; the shell of Terehra, though longer, is not of such 

 overbalancing proportions, it is more truly acuminated, the weight is chiefly 

 at the base, and the animal obtains a comparative facdity of locomotion by 

 the force with which it is able to secure its muscular disc to the place 

 of attachment. 



The Terehra chiefly inhabit the eastern world, and are confined to warm 

 temperatures ; one small species, only, reaching so far north as the Medi- 

 terranean. The weU-known T. maculata of Ceylon is the largest of the 

 genus, the greater number of species vary from three to four inches in 

 length, and are characterized by an interesting variety of sculpture and 

 design. The most elongated and remarkable species is the T. jiretiosa, 

 which I have selected as an example on account of its rarity ; only two or 

 three specimens have yet been seen. 



