418 PYKAMIDELLIDjE. 



Having examined some of these so-called species, I am 

 bound to add them to the synonymy of Chemnitzia pallida -, 

 one of the most variable species as regards the shell ; but the 

 animals of all these spurious articles have the unvarying distin- 

 guishing character of C. pallida, which is absent from all the 

 other Chemnitzia that can in any way be confounded with this 

 group, I mean the liberal, though irregular aspersion of 

 many of their organs with minute sulphur-yellow or gold- 

 coloured spots and points ; and above all, the organs of their 

 animals are similar. This species is an inhabitant of all the 

 zones, and receives that impress as to form and size which 

 results from the incidents of the respective localities; these 

 causes have doubtless led to the formation of the pseudo- 

 species, which I think only in some cases can claim even the 

 distinction of varieties. 



We add a few remarks on the variety of the pallida termed 

 by some authors rissoides, and considered by them a distinct 

 species. We do not concur in that opinion, as it has all the 

 characteristics of the "pallida." This variety, like the type, 

 varies greatly in size and contour j scarcely two specimens 

 will be found congruous ; every 100 yards of coast appears 

 to possess its variety. It is a most ubiquitous animal, being 

 taken in every kind of sea-bottom, mud, sand, shelly debris, 

 and Nullipores; the products of the littoral grounds are 

 usually of minor bulk, those of the muddy districts the 

 largest. 



CH. PLICATA, Mont. 



Turbo et Odostomia plicata, auctorum, et Brit. Moll. iii. p. 271, 

 pi. 98. f. 1, 2. 



The animal throughout is pale frosted-yellow, inhabiting a 

 spiral shell of six or seven slightly raised volutions. Mantle 

 simple. Rostrum short, flat, entire, slightly bevelled or pared 

 off at some points of the superficies, gradually dilating to the 

 terminus, which sometimes appears truncate, but often assumes 

 the figure of a shallow, hollo wed-out, subcircular disk. The 

 tentacula are triangular, bevelled, broad, flat, rather longer 

 than in its congeners of the same size, and terminate in 



