Messrs. Hancock and Emblcton on the Anatomy o/Eolis. 197 



perception of sonorous undulations. Since it has been ascertained 

 that E. 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 Eolisy we have endea- 

 voured, 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 Eolididte and other allied genera, — that the 

 functions of respiration, chylification, and the secretion of bile 

 are cumulated in the branchial papillae, 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 Eolis 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, recapitidate 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 



