TROCHUS. 333 



It resembles the variety data of T. zizyphinus in size, 

 shape, and every other particular, except in having a 

 bright polish, and darker or more vivid hues. Linne 

 noticed that T. conulus was so very much like T. zizy- 

 phinus as to be almost a dwarf variety of it, but that 

 the former had a prominent ridge or line between each 

 whorl. Pennant figured a small-sized T. zizyphinus as 

 T. conulus. The one may be the northern, and the 

 other the southern form of the same species ; and some 

 of my references in respect of the geographical distri- 

 bution of T. zizyphinus may be applicable to T. conulus 

 only. 



16. T. oc'cidenta'lis*, Mighels. 



T. occidentals, Migh. in Proc. Boston Soc. Nat Hist. i. p. 49. T. ala- 

 bastrum, F. & H. ii. p. 497, pi. Jxvi. f. 7, 8 (as T. formosus). 



Body creamcolour or white, with irregular streaks and 

 specks of purplish-brown, or tinged with yellowish -brown : 

 mantle slightly projecting beyond the shell, and finely ciliated 

 at its edge ; lappets roundish-oval and thin, one between each 

 eye and the foot : head conical, thick, flexible (like the trunk 

 of an elephant), closely fringed or scalloped in front ; no veil 

 was perceptible in any of the specimens examined by me, 

 although Forbes says that " the capital lobes are minute and 

 imperfectly developed : " tentacles filiform and slender, finely 

 setose, with often a brown line down the front, and another 

 on each side : eyes large, on short stalks : foot thick and broad, 

 truncated in front, with a triangular expansion or lobe (like 

 an auricle) on each side of this part, and bluntly pointed be- 

 hind ; the posterior half is raised into a long triangular ridge, 

 whence there is a gradual slope to each side, with a depression 

 in the middle ; the upper edges are irregularly fringed or studded 

 with short papillae, between which issue the lateral filaments or 

 appendages; sole exquisitely fringed : appendages 3 (sometimes 

 4) on each side, resembling the tentacles in every respect 

 except in being smaller. The whole body is covered with 

 cilia. 



Shell pyramidal, with a somewhat turreted outline and a 



* Belonging to the west. 



