Messrs, Hancock and Embleton ov the Anatomy of Eolis. 197 
perception of sonorous undulations. Since it has been ascertained 
that EL. punctata and Dendronotus arborescens do emit sounds, it 
seems probable that these organs may be provided for the per- 
ception of such. These crystalline-looking bodies are stated to 
be calcareous, but on treating them with acetic acid we did not 
find after the lapse of some time that any material change had 
taken place. 
In investigating the different organs of Eolis, we have endea- 
youred, as we at first proposed, to place their anatomy and phy- 
siology in as clear and correct a light as possible, and to show in 
what particulars we differ from M. de Quatrefages, and now in 
terminating this memoir we are in a position to state, that his 
anatomical details are with regard to every organ more or less 
erroneous. 
We are very glad therefore to learn that he has been led to 
forgo his proposed order Phlebenterata, and we may express a 
hope that the whole hypothesis of Phlebenterism as applied to 
the Mollusca will soon be abandoned. This Phlebenterism, which 
was first brought to light by M. Milne-Edwards, and maintained 
by him and M. de Quatrefages and some of the most distin- 
guished French naturalists, and which implies a fusion of the 
digestive and vascular systems by a marked degradation of the 
latter that reduces these Nudibranchiata almost to the condition 
of the Radiata, is, if we understand it at all, founded on the as- 
_ sumption that no veins or true auricle any more than a true in- 
testine exists in the Kolidide and other allied genera,—that the 
functions of respiration, chylification, and the secretion of bile 
are cumulated in the branchial papille, and that the ramifica- 
tions of the digestive system in some way or other supply the 
deficiency which was supposed to exist at the venous part of the 
circulation, and also distributed the digested portions of aliment 
throughout the body. But on full consideration of what is put 
forth as Phlebenterism in the Mollusca by the French naturalists, 
we confess our inability to arrive at a precise understanding of 
what is meant by the term. We believe we have in our account 
of the anatomy of Holis brought forward evidence enough to 
overthrow Phlebenterism, such as we conceive it to be as applied 
- to these animals, and we will now in conclusion, and as briefly as 
we can, recapitulate what we have before advanced, adding some 
new observations which now occur to us. 
First, we have demonstrated that the vascular system is not in 
that state of degradation supposed by the French savans. We have 
shown a well-formed heart, consisting of ventricle and auricle, in- 
closed in a pericardial sac, the ventricle giving off an aorta that 
branches away to supply the principal viscera and the foot. The 
