280 BULLIDA. 
slender, open groove, which by the muscular contraction of 
the sides can be closed so as to form a canal, extending from 
the orifice of the verge to the entrance of the common cavity, 
must be regarded as a continuation of the vas deferens of the 
testis, which passing under the matrix, or through it—which 
of the positions is doubtful—unites with the open canal that 
terminates at, but does not pass into, that organ, and thus the 
vivifying influences are enabled to make the necessary contact. 
M. Cuvier’s figure of the branchial plume presents a vertical 
and partly horizontal face. Having examined many specimens, 
it appears to me to be a single regular crescent-shaped plume 
of eighteen or twenty short coarse strands, having the artery 
in the centre, lying in a crypt transversely between the vulva 
and the anus, floating free, except where under the mantle it 
is fixed to its roof and to the back of the animal. The heart 
is oval, white, and with the auricle placed as usual in a peri- 
cardium, at the base of the branchiz. With regard to the 
veins and arteries I have not attempted to trace them; the 
circulation is of course complete; but if, as in Aplysia, there 
are any peculiarities attached to it, I do not think that they 
will easily be detected im so small an animal. There is no- 
thing particular in the muscular system ; it exhibits the usual 
masses of transverse and longitudinal fibres, which throw off 
from the internal surfaces the necessary muscular filaments. 
The Bulla hydatis may be considered as the type of the general 
aspect of the anatomy of the family of the Bullide. 
The shght rectifications I have ventured to suggest, even if 
established, in no way detract from the general accuracy of 
the great anatomist I have alluded to; if I am right in my 
suggestions, it is entirely due to having at my disposal nume- 
rous living specimens; but M. Cuvier, I infer from his 
memoirs, had often only one or two indifferent specimens 
from spirit. His merits and labours exhibit a noble example 
of what may be accomplished by assiduous application, com- 
bined with a mighty genius; he is the pilot and Columbus 
of modern malacology, and his successors have little more 
merit than as “ imitatores ;” for what we know he has taught 
us, and those who have gone beyond him in the useful 
