72 



determined. Of the species at present known, the T. bicarinata, is the 

 only one at all remarkable for its size and bristly appearance ; it is of a 

 fragile texture, and unlike the shell of any other genus. 



The species above alluded to is from Icy Cape; those collected by 

 Mr. Hinds, are from a much warmer region. 



1. acuminata, Jeffreys. 



2. Atlantica, Mutter. 



3. bicarinata, Broderip. 



Species 



4. borealis, Broderip. 



5. cancellata, Hinds. 



6. costellata, Courth. 



7. flavida, Hinds. 



8. inermis, Hinds. 



9. umbilicata, Magill. 



Trichotropis bicarinata. 

 bristly epidermis. 



Figure. 

 PI. 7. Pig. 33. Showing the aperture and 



Genus 15. DOLIUM, Lamarck. 



Animal; disc ovately oblong, large, very thick and muscular, 

 subauriculated on each side in front ; head large and rather 

 flattened, with an unusually long conical tentacle on each side, 

 at the base of which are the eyes, fixed upon short peduncles ; 

 trunk capable of considerable elongation, branchial siphon ample, 

 reflexed. 



Shell ; thin, rotundately swollen, light and ventricose, ribbed 

 transversely, but not longitudinally ; columellar lip thin, widely 

 expanded, outer lip fimbriated or crenated. 



The Dolia constitute a limited, but very characteristic group, distinguised 

 by their size and muscular strength, and by the voracity and comparative 

 activity of their habits. The head is furnished with a long retractile 

 trunk, which they have the capacity of rapidly protruding and withdrawing ; 

 they have also an ample disc, and " when the animal desires to swim/' 

 says M. Deshayes, who had an opportunity of observing the Bolium on the 

 shores of the Mediterranean, in the course of Ins expedition to Algeria, ' ' he 

 swells it out with an enormous quantity of water, which is imbibed through 

 certain pores". I have given representations of three different species of 

 this genus with the soft parts, in order to show how much greater variety 

 and brightness of colour is exhibited in the animal, than in the shell; in 

 the B. perdix, we find a bright blue-striped animal with a dull brown shell, 

 and the B. olearium and pomum, with pale sallow yellowish shells, have 



