APPENDIX. 349 



the Eolidina, I proved : firstly, that the intestine rami- 

 fies and sends prolongations to the dorsal papillae, which 

 had hitherto been regarded as ordinary branchiae * ; 

 secondly, that the liver does not exist as a distinct 

 organ, but that the intestinal prolongations, of which I 

 have spoken, are invested with a granular covering, 

 resembling certain hepatic organs ; and, thirdly, that 

 the food penetrates through the entire extent of the 

 ramified canals of the intestine. 



At the same time I found in the Eolidina a heart and 

 a tolerably well developed arterial system, but I could 

 not distinguish any veins ; nevertheless, I was so 

 thoroughly imbued with the ideas of Cuvier that it was 

 long before I was willing to admit the non-existence of 

 these vessels. Nor was I convinced that there were 

 really no veins in the Eolidina, until I had followed the 

 same blood-corpuscle throughout its entire circuit until 

 I had seen it issue from the heart, and pass through the 

 arteries by whose walls its movements were regulated, 

 and until it was conveyed through every part of the 

 general cavity, and finally carried back to the heart. 



The species of which I have spoken was the subject of 

 my first memoir, which was received without much op- 

 position. I had looked upon the Eolidina merely as a 

 degraded and consequently as an exceptional species ; 

 but 1 laving had occasion at Brehat to study several of 

 the allied species, I was led to take a more general view 

 of the subject. As I could not suppose that Cuvier and 

 Blainville f had been deceived in reference to this 



* Previous to my researches, Milne Edwards had ascertained 

 this fact in the Calliopea of Risso ; and Loven, a Swedish naturalist, 

 had also recognised it in several species. 



f Cuvier and Blainville had at their disposal Eolidse, whose size 

 adapted them admirably for dissection, yet neither of them have re- 

 ferred to the remarkable characters which I have described in respect 



