ALLMAN. 597 



judges in this country — from Alder, Hancock,* Embleton, 

 and Allnian. And, indeed, M. de Quatrefages, continuing 

 his studies, had himself partially detected the errors that had 

 misled him ; so that in the beginning of the year 1845, he 

 admitted the order could not be maintained, but must relapse 

 into that from which he had attempted to dismember it. 

 This change of view was made, he says, partly from personal 

 observation, but principally induced by the discoveries of 

 Milne-Edwards and Valenciennes. "In fact," he adds, " the 

 imperfect condition of the circulatory apparatus, which I had 

 considered as a symptom of organic degradation peculiar to 

 the Phlebenteres, being found in an entire section or branch 

 of the Mollusca, the relative importance I had attributed to 

 it disappears. Moreover, I had foreseen that, in reference 

 to their respiratory organs, forms intermediate to the Phle- 

 benteres and the normal Nudibranches would be found. The 

 characters which, therefore, rested on such considerations are 

 not sufficient to establish an order ; and, accordingly, 1 am 

 brought to reduce the Eolides and allied genera to the rank 

 of a family." This family M. de Quatrefages divides as be- 

 fore, and as we have already explained, merely altering the 

 family denominations into that of Tribes, thus, 1, " Dorsi- 

 branches proprement dits ;" 2, " Enterobranches Remibran- 

 ches ;" and 3, " Dermobranches."-j- 



Also, in 1844, but subsequently to the publication of M. 

 de Quatrefages' earliest opinions, which he successfully con- 

 troverted, Professor Allman proposed a classification of the 

 Nudibranches founded on the belief that the ramified appa- 

 ratus connected with the stomach in the Eolididas " is truly 

 a hepatic system, and affords an interesting example of the 

 reduction of a gland to one of its simplest conditions. "J 



* " This order wo have already objected to, both on account of our opinion 

 of the incorrectness of the theory which the name involves, and because it 

 breaks up the order Nudibranchiata, which appears to us to be a natural 

 group, well-distinguished by their external characters, and, though somewhat 

 different in their internal anatomy, showing modifications, in that respect, 

 so gradual that it is scarcely possible to draw a line of distinction which 

 would separate them even into families." — Ann. and Mag. N. Hist. Ser. 2. i, 

 404. ; and also iii. 197. 



t The characters of these tribes M. de Quatrefages has fully described in 

 a " Resume" des Observations faites en 1844 sur les Gaste'ropodes Phleben- 

 teres," contained in Ann. des Sc. Nat. (1848), x. 121—143. 



% " We have in these gastric ramifications one or more offsets from the 

 lining membrane of the alimentary canal greatly extended and terminating 

 in culs-de-sac, where doubtless resides the function of elaborating the biliary 

 secretion. We have just such an appearance as a careful preparation of 

 glandular structure would present with all its component ducts and terminal 

 culsile-sac accurately disentangled ; we have in fact in the Phlebenteric 



