TUEEITELLA. 331 



Ccecum trachea very active, but it is far surpassed by this 

 animal; I put one of each in a watch-glass of sea- water, and 

 with a cameFs-hair brush gave them a fair start, but the little 

 one beat its competitor hollow, and accomplished a space of 

 2 inches in 55 seconds ; thus affording a proof, even in the 

 Mollusca, that nature compensates for the small volume of 

 the minute beings in giving them greater energy, vivacity and 

 quickness. This creature I found by admeasurement to be 

 2*0 th of an inch long, and y^th of an inch in diameter. 



I have been thus particular, as it can fall to the lot of very 

 few malacologists to see this curious species alive. 



TUERITELLA, Lamarck. 

 T. COMMUNIS, Eisso et Auct. 



T. communis, Brit. Moll. iii. p. 1?2, pi. 89. f. 1,2, 3 ; (animal) pi. I.I. 



f. 4. 

 Turbo tenebra, Montagu. 



The incidents and peculiarities of this genus, of only one 

 British species, in regard to its connection with the Holo- 

 stomata and removal to this family, are so fully stated in the 

 subjoined account of the comparison of Turrit ella with Ver- 

 metus, as not to require further remark. 



Animal elongated, inhabiting a brown, spirally ridged, 

 turreted shell of 16-18 tapering volutions. Mantle yellow, 

 loose, ornamented at the upper part with a fringe of the same 

 colour, of seven long and as many shorter strands, the longer 

 ones being fimbriated at both edges, presenting a foliaceous 

 aspect. In Vermetus, Philippi says, " mantle entire;" but 

 Sassi, " emarginate." The head is a small, flat, rounded 

 muzzle, which always rests on the foot, yellow, with close-set, 

 transverse, fine dark lines; in Vermetus the head is similar. 

 Tentacula rather long, conical, pointed, tumid at the bases, 

 yellow, with eyes at the external angles on only slight pro- 

 minences; in Vermetus, teste Philippi, four tentacula, which 

 however means, as regards two of them, eyes on swollen 

 pedicles, as in Trochus. The foot is very short before and 

 behind, scarcely extending to the first volution, yellow under- 



