524 APPENDIX. 
C. interstincta is a variety, or really distinct, may be question- 
able. This pomt requires further 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 opimion, 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. 482.) 
In this species the rostrum is attenuated in its course from 
the tentacula to near the termination, where it assumes a 
