48 



Genus 3. MITRA, Lamarck. 



Animal; disc small, oblong, oval behind, squarely truncated in 

 front; head and tentacles small, eyes situated sometimes towards 

 the middle of the tentacles, sometimes pedunculated and towards 

 the base; respiratory siphon thin; trunk susceptible of very 

 considerable elongation. 



Shell ; turreted or fusiform, emarginated at the base, spire mostly 

 sharply acuminated, apex narrow, varying in length ; columella 

 a little recurved at the base, lower plaits the smaller. 



The Mitres constitute a numerous division of the family Columellata, 

 distinguished from the Volutes by a very important association of cha- 

 racter ; their shells are long and turriculated, and there is a marked change 

 in the arrangement of the columellar plaits, winch, instead of increasing, 

 diminish in size as they descend ; the animal is very small ; the head is of 

 the form of a triangle, at the basal corners of winch are the tentacles, with 

 the eyes situated sometimes towards the middle, sometimes towards the 

 base, upon short peduncles ; the respiratory siphon is small and not dilated 

 into lobes at the base, and the trunk is capable of remarkable elongation ; 

 lastly, their habits vary, and they differ in their geographical limits. 



It is easy to conceive that a small mollusk, producing a ponderous tur- 

 riculated shell like the ' Bishop's Mitre ', (31. episcopalis) would naturally 

 be of a much more sluggish disposition than one whose shell is sup- 

 ported by an ample muscular disc like the ' Bat Volute ' (V. vespertilio) ; 

 and the Mitre is accordingly described by M. Quoy and Gaimard as an 

 "animale apathique", a creature of limited sensibility, whose activity is 

 necessarily restrained by the over-balancing proportions of its shell. It 

 is related by these illustrious circumnavigators, who were the first to 

 discover the Mitre in a living state, that they kept several healthy indivi- 

 duals for some time without observing any decided movement ; they are, 

 however, provided in this comatose state with the faculty of elongating their 

 trunk to an extent not enjoyed by any other genus ; the extremity of it is 

 furnished with a kind of dentated chewing apparatus, and the animal is 

 enabled to exert this destructive organ in all directions for the capture of 

 food, with little apparent effort, and without altering its position. 



The peculiarity alluded to in the geographical distribution of the Mitres, 

 is, that they are rarely found in places inhabited by Volutes j the Philippine 

 Islands, for example, are probably the richest spot in the world for Mitres ; 

 during Mr. Cuming's four years sojourn in that locality, he collected be- 

 tween two or three hundred species, yet scarcely a Volute presented itself; 



