524 APPENDIX. 



C. interstincta is a variety, or really distinct, may be question- 

 able. This point requires farther investigation. 



I have stated that the true C. interstincta has usually a 

 fold or tooth on the columella, but that it is not uncommonly 

 found without it. I now amend that opinion, and believe 

 it is never without a tooth : the error has arisen from the 

 casual introduction and mixture in collections of young spe- 

 cimens of the C. indistincta, which are very similar, but 

 invariably without the tooth. I also remark, that the tumid 

 shell, whether it is a variety of C. interstincta, or distinct, is 

 never without the tooth. 



With these very minute shells, which closely resemble each 

 other, and whose animals do not differ greatly, first im- 

 pressions sometimes prove erroneous, but continual examina- 

 tion of both shell and animal at last elicits the truth. 



In the reproduction, for "tentacula rather long, slender," 

 read " rather short and broadish." This correction shows 

 the difficulty in these minute creatures, of seizing, in the 

 ever- varying tentacular and other organs, the precise points 

 for description. 



CHEMNITZIA INDISTINCTA. (P. 428.) 



We have again examined, in the same vase, the animal of 

 this species, and its variety termed by authors C. clathrata, 

 and still retain our original opinion, that they are identical ; 

 both vary somewhat in colour, the one having a bluish-white 

 cast, the other a pink one, and they also present different 

 degrees of slenderness and tumidity of contour. Neither 

 has a trace of fold or tooth on the columella. 



The rostrum is moderately grooved on its upper surface as 

 far as the basal tentacular coalition, at which point, somewhat 

 below the eyes, a prominence, caused by a slight degree of 

 contraction, marks well the minute fissure for the issue of 

 the proboscis. 



CHEMNITZIA DECUSSATA. (P. 432.) 



In this species the rostrum is attenuated in its course from 

 the tentacula to near the termination, where it assumes a 



