BRITISH NUDIBRANCHIATE MOLLUSCA. 9 



apparatus of the stomach, and the presence or absence of veins in the circulatory system. It 

 is unnecessary here to mention in detail the whole of the papers communicated to the Academy, 

 or published in the French journals in connexion with this controversy, which was carried on 

 for some time with considerable energy. We may state, however, that M. de Quatrefages 

 admitted the existence of some errors in his earlier papers, and was willing to give up the 

 Pfilebenterata as a separate order, but still maintained the correctness of his views on the 

 gastro-vascular system and the degradation of types. He proposed to retain the term 

 Phlebenterism, in a more extended signification, to designate that species of degradation which 

 consists in the union of different functions in one system of vessels, to be found, according to 

 his views, in all divisions of the animal kingdom. 



We may perceive in the desire to discover proofs of this theory the source of most of the 

 errors with respect to facts which we cannot doubt that M. de Quatrefages has committed in 

 his Memoir on the TUeb enter ata. Since its publication we have discovered on the English 

 coasts undoubted examples of most of the genera there described, and we have been able to 

 demonstrate* that no degradation of type, to the extent that he describes, is to be found in any 

 of them. In every case we found a heart and blood-vessels more or less complete, and the 

 anal opening was present in all. So far as regards these points, therefore, we may dismiss as 

 purely imaginary the extreme degradation of type which some of these little animals were 

 supposed to exhibit. 



The matter in dispute was ultimately referred to a new commission of the Academy of 

 Sciences, whose report, drawn up by M. Isadore Geoffroy Saint Hilaire, was presented to the 

 Academy on the 13th of January, 1851. f The commission, after considering attentively the 

 evidence submitted to them by the contending parties, came to the resolution, that the 

 existence of. a heart, arteries, and branchio-cardiac vessels in the Phlebenterate Mollusca is 

 proved, and that a regular circulation does exist, but that whether it is completed by a system 

 of veins or by means of lacunes is still open to dispute. With respect to the functions of the 

 branched vessels called gastro-vascular, the commission think that further evidence is 

 desirable, but from the existence of a system of vessels specially appropriated to the circulation, 

 as well as of organs performing (at least in part,) the office of respiration, they think that the 

 threefold office assigned to them by M. de Quatrefages can scarcely be maintained. 



Meanwhile, M. de Quatrefages brought the subject before the Biological Society of Paris, 

 and a commission of that Society was likewise appointed for its investigation. After a careful 

 examination of the subject, they agreed to a report which was drawn up by Dr. Charles 

 Robin. | This able report, which is extremely elaborate, filling a pamphlet of 132 closely 

 printed pages, appeared very nearly at the same time with that of the Academy. On the two 

 main points in dispute the commission came to the conclusion that M. Souleyet is correct, and 

 dismiss the idea of Phlebenterism as untenable. They consider the ramifications of the 

 digestive system to be true biliary ducts in connexion with a divided liver, and that they do 

 not fulfil any other function than the usual one of that organ. They, moreover, consider that 

 the circulatory system in these animals {Bolts, Jctceon, &c.) is complete, the so-called lacunes 

 being similar to the blood-sinuses known to exist in particular cases throughout all departments 



* 'Arm. Nat. Hist./ v. 13, p. 161; v. 18, p. 289; and 2d series, v. 1, p. 101. 



t ' Comptes Eendus Hebdomadaires/ v. 32, p. 33. 



% 'Rapport h la Societe de Biologie/ &c, par M. le Dr. Charles Bo-bin. Paris, 1851. 



2 



