2 Prof. G. J. Allman on a new genus of Mollusca. 
in some way connected with their singular, almost amphibious 
habits. 
I collected several specimens which I placed in spirits, but I 
unfortunately neglected to examine with any accuracy the ani-. 
mal in its recent condition, and it was not till several months 
afterwards, when I was making a complete survey of my col- 
lection, that the salt-marsh Nudibranch received the attention to 
which it was entitled. On sending specimens to Messrs. Alder 
and Hancock, as the first authorities on the subject, their exami- 
nation coincided with my own in proving our little mollusk to be 
a creature of great interest. 
The specimens having been preserved in spirits (a circumstance 
which in the case of the invertebrate animals demands from the 
naturalist the greatest caution in his attempts to establish zoo- 
logical characters), our examinations were by no means so satis- 
factory as we could have wished ; not however being restricted in 
our investigation to a single specimen, we were enabled in some 
degree to counteract the difficulties which the state of the speci- 
mens threw in the way of our inquiries, and succeeded in esta- 
blishing characters by which the Nudibranch of the salt-marsh 
appeared to be generically distinguished from all hitherto de- 
scribed. 
Perhaps the most anomalous character is the absence of ten- 
tacula. Indeed so strange is this fact, that for a long time I 
thought it was only apparent, and the result of a badly-pre- 
served state of the specimens. A most careful examination how- 
ever of several individuals having failed to detect any trace of 
these organs, I have no hesitation in concluding that their absence 
is real, and this will therefore constitute an important generic 
character. 
Another highly interesting character is the dorsal and median 
termination of the rectum, which opens near the posterior extre- 
mity of the body on the mesial line of the back by a small tu- 
bular orifice, a most unusual though not unprecedented condi- 
tion in the Kolidide. 
Our mollusk has been dissected by Messrs. Hancock and Em- 
bleton, but neither these gentlemen nor myself could detect any 
trace of corneous jaws. They have succeeded however in demon- 
strating a linear, jointed tongue covered with spines, or what they 
are rather inclined to consider as flat plates. A system of gastric 
ramifications seems also to exist, but from the state of our speci- 
mens we could make out nothing satisfactory as to its distribu- 
tion. 
From the facts now mentioned I had little difficulty in con- 
vincing myself that the mollusk at present under consideration 
possessed characters which excluded it from all hitherto esta- 
