Mr. W. Clark on Ceecum trachea and C. glabrum. 181 
side of which, at the usual point, may be seen a minute pale red 
branchial leaflet which puts on the appearance of there being 
two, a large and a smaller one, as in the canaliferous Gasteropoda ; ; 
but here, ‘though we cannot vouch that there are not two, we are 
inclined to “trols there is only one, with a divergence from its 
base of a part of its surface ; the very marked canal seems neces- 
sary for the entrance of ihe branchial water, im consequence of 
the neck of the animal, when at rest, being so closely embraced 
by the fleshy muscular circular mantle, but in marching order it 
is protruded to an extraordinary extent. 
The stomach was distinctly observed, and is an oblong bursi- 
form organ, yellowish white and granular without, but on being 
opened presents a dark lead- coloured cavity, fortified by strong 
transverse muscular bands or fillets. From it arises a very long 
convoluted intestine, and when extracted exhibited the usual fecal 
matters ; it appeared to coast the liver and ovarium, amongst 
the folds of which it makes a double, as is usual with the regular 
Gasteropods, then progresses to the right side, where the minute, 
elongated, oval, conically pomted pellets were observed to be 
ejected. 
The ovarium ts dark red-brown, aspersed with the most minute 
darker points, like the finest sand, with its posterior extremity 
fixed in the hollowed-out chamber of the terminal process of the 
shell ; it then extends to the stomach accompanied by the liver 
in alternate transverse portions ; this organ is a light greenish 
mass formed of larger granules than the ovarium, and the con- 
trast in colour of the two substances caused them to be observed 
without difficulty 
The neck admitted of a close examination, and did not exhibit 
the slightest traces of external reproductive organs; it would 
then appear that the animal must depend on its own influences, 
but there are doubts; and from the concordance of all its organs 
with a large class of the Pectinibranchous Gasteropods, it may, 
like them, be unisexual, though the organs have escaped detec- 
tion ; but in all the specimens ; examined the ovarium was present 
in the usual place, and im no instance appeared to be replaced by 
the testicle, but the discrimmations of such minute organs can- 
not be depended on. 
The foot is short, narrow, and truncate anteriorly when in ac- 
tion, sloping posteally to an obtusely pointed or rather rounded 
termination, on the upper part of which end is fixed the strong, 
circular, corneous, black-brown operculum, smooth and conical on 
the surface attached to the foot, concave without, and from its 
centre seven or eight fine close-set spiral lines, not concentrical, 
fill up the area. 
The animal is not at all shy ; it shows itself in all directions, 
