Mr. W. Clark on some of the Animals of the Chemnitzise. 197 



fluid ? Can all the Gasteropoda, at the upper angle of the aper- 

 ture on the right side, have branchial conduits independent of 

 the reception of the water into the respiratory vault, under the 

 lax mantle, by the protrusion of the neck and head of the 

 animal ? 



The presence of a proboscis brings this genus very near to 

 the Canaliferce ; but the Eulimce arc still nearer, as they have no 

 head or rostrum, and the proboscis issues nearly at the fork 

 between the tentacula, as in the Muricidal families. This state- 

 ment renders it necessary to cancel that part of one of my papers 

 wherein I doubt the evolution of a strict proboscis, but after 

 what I have seen that question is set at rest. 



The rostrum varies greatly in the proportions of its arcuations, 

 scissions, and points of attachment to the foot ; in the Chem. uni- 

 dentata it is plain and truncate, in C. acuta it forms an open 

 subcircular channel with a cochleariform termination, and in 

 Chem. conoidea it is cloven nearly to the base, simulating a 

 second pair of tentacula. 



I have omitted to remark that the orifice of the rostrum is not 

 precisely in the position of the proboscidal fissure of the Muri- 

 cida ; it is not quite so low in the fork, though exactly under the 

 tentacula at the point of the invasion of the neck, and its con- 

 tinuation, the rostrum, by those organs ; this position is proved 

 by the proboscis when evolved lying upon the rostrum, and by 

 its breadth equalling that of the neck, a point I formerly doubted, 

 and entirely hiding that organ from view. This leads me to say, 

 that for the fourth time, a few days since, I witnessed the emis- 

 sion of the proboscis from a specimen of one of the slender 

 varieties of Chem. acuta : I had an excellent view, as the animal 

 exserted and withdrew it several times, which was not the case 

 before ; it was not quite so slender at the point, nor so much 

 arcuated as in Mr. Alder's figure ; its orifice was perfectly seen. 



From the above remarks and the descriptions that follow, 

 together with those recorded in former papers, which com- 

 prise animals of the genera Chemnitzia, Odostomiay and Euli- 

 m£lla of modern authors, I submit to naturalists the propriety 

 of merging the two latter in Chemnitzia, an appellation that 

 fortunately has no other significancy than that of compliment to 

 a laborious author in this branch of natural history. The simi- 

 larity of the organs of the animals of the three genera, so far 

 from affording essential generic characters, does not suffice with- 

 out the assistance of the shell for specific distinction. Surely 

 the Chem. rufa and C. elegantissima should not be separated from 

 the smoother Chem. Scilke and C. acicula, merely because the 

 one is smooth and the other ribbed : if so, to be consistent, it 

 would be necessary to separate the smooth Chem. pallida from 



