366 PLEUROTOMID^. 



3. D. Leufro'yjl**, Michaud. 



Pleurotoma Leufroyi, Mich, in Bull. Soc. Linn. Bord. ii. (1828) p. 121, 

 f. 5, 0. Mangelia Leufroyi, F. & H. iii. p. 4G8, pi. cxiii. f. 6, 7, and 

 (animal) pi. BE. f. 1, as M. Lefroyi. 



Body white, with a faint tinge of yellow (" sometimes 

 slightly tinged with purple," F. & H.) : pallial tube conical, 

 short, not protruded beyond the canal of the shell : tentacles 

 cylindrical, rather short (" long and slender," F. & H.), with 

 blunt tips ; they widely diverge, and sometimes assume the 

 shape of the letter Y : eyes on thick stalks united with the 

 tentacles at their outer base : foot (" very large and expanded," 

 F. & H.) broader and indented in front, with small ear- shaped 

 corners, bluntly pointed behind. 



Shell broad towards the base, more or less solid according to 

 habitat (being much thicker in the lower part of the littoral zone 

 than in deep water), and for the same reason either opaque or 

 semitransparent, rather glossy : sculpture, several strong curved 

 longitudinal ribs, which extend to the base but do not cross 

 the fissural groove or subsutural area; the body-whorl has 

 from 14 to 18 ribs, the next 14 to 16, the next 12 to 14, and 

 the next 10 to 12, when they rapidly decrease in number, 

 disappearing towards the apex ; the rib immediately behind 

 the mouth is not disproportionately large ; all the whorls ex- 

 cept those which compose the apex are encircled by fine thread- 

 like ridges or striae, which are very close-set and occasionally 

 alternate in size ; of these may be counted more than 30 on 

 the body- whorl, 12 on the next, 8 on the next, 6 on the next, 

 and so on ; the third whorl from the top sometimes is indis- 

 tinctly keeled in the middle ; fissural groove not only having 

 3 or 4 slight spiral ridges, but crossed by numerous fine curved 

 striae ; the points of intersection on the upper whorls form 

 oblong nodules, with the major axis in the direction of the 

 spire, and are now and then muricated or prickly ; the whole 

 surface is microscopically and closely marked by the lines of 

 growth ; top whorls exquisitely reticulated by curved striae, 

 which cross each other diagonally, like the wirework of a 

 fire-guard : epidermis thin, yellowish -brown, persistent only 

 in the fissural groove : colour whitish, passing into cream- 

 colour, variegated by irregular purplish- or reddish-brown 

 blotches, which are arranged in two very broad zones or bands 



* A complimentary dedication by Professor Michaud to his friend 



M. Leufroy. 



