110 Mr. W. Clark on the Chemnitzise. 



Chemnitzia Sandvicensis, Walker, Test. miD. rariora. 

 Odostomia doUoliformis, nonnuU. 



Animal inhabiting a wliite spirally striated subglobose shell of 

 four volutions, with a reflexed apex and strong fold on the pillar. 

 The colour throughout is hyaline pale azure. Mantle even with 

 the apertural margin, except a slight canaliculation at the upper 

 angle of the right side. The proboscidal muzzle, which some 

 call the mentum, is the exact characteristic essential shape of the 

 tribe ; in quietude it scarcely extends to the anterior margin of 

 the foot, but on the march it considei'ably precedes that organ. 

 The tentacula are proportionately longer than in its congeners, 

 not so triangular, nor furnished with such broad lateral mem- 

 branes, nor do they coalesce so decidedly as in some species to 

 form a veil; nevertheless they are bevelled and subtriangular, 

 with the eyes at the internal bases. The tip of each tentaculum 

 has a point of flake- white, giving, I think, only the appearance of 

 a slight inflation, or it may be real for a limited period, caused 

 by the contraction of the muscle of the tentaculum. 



The foot is a singular deviation from that organ in the typical 

 species ; it is short, broad and blunt, truncate anteriorly, there 

 often twisting itself into acute angles, which, when they happen 

 to fall in a line with the true tentacula, give the appearance of a 

 pair on each side, but a change of position instantly makes that 

 appearance disappear ; the anterior third portion of the foot is 

 somewhat contracted ; at this point a transverse groove appears, 

 from the centre of which another longitudinal one proceeds to 

 the posterior end, dividing the foot below the transverse portion 

 into two suboval lobes, each rounded at its termination and 

 separated by an emargination : whether these grooves are only 

 depressions or solutions of continuity, 1 could not in so minute a 

 creature satisfactorily determine ; but the appearance is a foot 

 formed of three lobes, an anterior and two suboval lateral ones 

 with rounded termini. This is the great singularity, and mala- 

 cologists would constitute a genus for it, but in all the essential 

 points it is a decided and typical Chemnitzia. The operculum 

 is fixed on a plain, not extended lobe ; it has the flap-process or 

 apophysis of the tribe, not in the same plane, but inflexed at 

 right angles ; on each side the notch that receives the tooth it 

 is cartilaginous and flexible in this species, and the strife of in- 

 crement range in elliptical curves, as in the typical Chemnitzia 

 pallida. 



The animal is not lively, at least the only one I have examined 

 was not so, and it is possible more active creatures, which are 

 exceedingly rare, may cause some modification of the points de- 

 scribed. It inhabits the littoral zone, and is unrecorded. Axis 



