Mr. W. Clark on the Chemnitzise. 113 



liculation. This is the first year I have succeeded in obtaining 

 live examples, which occurred in the littoral zone off Budleigh 

 Salterton, where in former years I have taken abundance of fresh, 

 excellent shells, but always without the inhabitant. The exist- 

 ing malacological notes on this animal are so meagre, that the 

 present account may almost be considered as that of an unre- 

 corded creature. 



Chemnitzia pusilla, Philippi, tab. 28. fig. 21. 

 Chemnitzia var. elegantissima, A.uglorum. 



A single live specimen of this very distinct species has occurred, 

 which enables me more decisively than in any of its congeners, to 

 insist on the position, that the eyes and tentacula are planted 

 across the rostrum (miscalled the mentum), which is an un- 

 doubted continuation of the neck. What has led to the idea that 

 the so-called mentum belongs to the foot, is that the pedal union 

 with the general body of the animal is in this tribe a little more 

 anteally advanced than in the Rissoce of similar proportions, 

 thus giving the neck, and its sequence the rostrum, an apparent 

 connection with the foot, w^hich, if really organically viewed, it 

 does not possess. 



It will only be necessary to notice the variations of the C. pu- 

 silla from its more stately congener the C. elegantissima ; it is, as 

 respects the shell, not half the size, much more tumid, and does 

 not taper in the decided manner of an example of that species of 

 similar size. The variations of the malacology are more pro- 

 nounced : the foot is much longer, extending on the march to 

 the third basal volution, and terminating in almost a needle 

 point ; whilst in the other, in a similar condition, it is quite 

 rounded, and does not reach beyond the body-whorl. In the 

 "pusilla," the tentacula when spread have the membranes united 

 almost to the extremities, which are minute and pointed, so that 

 they appear in action a single united leaf; in its congener they 

 are more triangular, less, though greatly, membranous, and do 

 not unite above half theii* length, and have very obtuse termi- 

 nations. The C. pusilla has a palish purple streak on each ten- 

 taculum, and on each side the rostrum ; this little fact is not 

 without its value, as it proves pretty clearly, that the rostrum, 

 miscalled the mentum, belongs to the neck and tentacula, and 

 not to the foot : in the C. elegantissima both the same parts are 

 hyaline-white. The two inhabit together the same littoral levels 

 at Littleham Cove. I now take leave of the Chenmitzia, and will 

 not again allude to them, unless I am compelled, as an " ultima 

 ratio," or to communicate decidedly new facts. 



I am, Gentlemen, your most obedient servant, 



William Clark. 

 Ann. fij- Maff. N. Hist. Ser. 2. Vol. viii. 8 



