PYRAMIDELLID®. 401 
termination to an antepenultimate one. I apprehend that 
these minute lobular appearances are due to the retractors of 
the tentacula concentrating at their tips a portion of the 
flake-white markings that are seen on those organs in all the 
Chemnitzie, and have no functional attribute beyond what is 
common to all tentacula. 
I have to add, in respect to the proboscis of Chemnitzia, 
that the organ is long, flattish, at least so in appearance, 
broad at the base, gradually tapering to its minute orifice ; 
the terminal half in the Ch. plicata example is tinged with 
dull sulphur-yellow, like that of the body, neck, and rostrum. 
After the proboscis was fully protruded, in about a second, 
I saw, through the hyaline texture, another organ unroll 
itself from base to point, from which one would infer, that 
the inner cylinder, if it be one, is not fixed to the inside 
terminus of the outer tube; or it is possible that the organ 
I saw ascend from the base of the proboscis, might be the 
very long, flat, unarmed lingual riband. 
With regard to what I term the rostrum, M. Loven says, 
“that the mentum has been misunderstood, and has generally 
been supposed to answer to the muzzle of Turbo, but that is 
not the case; this perfectly formed part is what I would call 
the mentum, the muscular mass, which is so extvemely deve- 
loped in Natica, covering part of the tentacula and mouth.” 
With respect to this extract, I cannot concur. The mentum, 
which I call the rostrum in Chemnitzia, has very little ana- 
logy with the upper part of the foot in Nadica, which I admit 
is always spread on the anterior part of the shell, as M. Lovén 
observes; but then I cannot call the anterior portion of the 
foot a mentum. What M. Loven calls the mentum in Chem- 
nitzia, 1s never spread on the upper part of the shell, and does 
not in any case touch it, and has no more connection with the 
foot than the muzzle of Rissoa; both are tied to the foot of 
their respective genera by a pedicle or bridle, which junction 
happens to be more anterior in Chemnitzia than in Rissoa, on 
which point see Ch. elegantissima and Ch. pusilla. 
I must here remark, that the labium, which exists more or 
less conspicuously in every Gasteropod, is particularly deve- 
2D 
