198 Messrs. Hancock and Embleton on the Anatomy o/Eolis. 



hepatic artery is wanting, but the fact of the Hver being minutely 

 divided among the branchial papillse, and the divisions being thus 

 placed in contact with aerated blood, explains this hiatus and ne- 

 cessitates it. The auricle receives three principal venous trunks, 

 each of which is made up of several branches from the skin ante- 

 riorly and posteriorly. These trunks have been called branchio- 

 cardiac by M. Milne-Edwards and his followers, under the convic- 

 tion that the whole of the blood passes to the heart from the 

 branchial papillse by them. We find nothing in Eolis to favour the 

 opinion that the whole of the blood is conducted by afferent vessels 

 from the body or intervisceral lacunse direct to the branchiae, 

 and thence exclusively by efferent vessels to the auricle. We see 

 that the network of lacunse in the thickness of the skin receives 

 the blood from the interior of the body, and allows it to flow 

 freely therein in all directions ; part of it doubtless passes to the 

 branchial papillae, but part also must go at once along the veins 

 to the auricidar part of the heart. In other words, the veins draw 

 their blood from the sinuses or lacunse of the skin, and this suc- 

 tion, so to speak, attracts the vital fluid at one and the same 

 time from the branchial papillse and the lacunse of the body, so 

 that the veins, instead of being merely branchio-cardiac, are really 

 both systemic and pulmonary together. We have likewise pointed 

 out small veins going from one of the viscera, the ovarium, into 

 the skin at the side of the body, and even a small vessel of 

 similar character going fi-om the ovarium into the posterior me- 

 dian trunk-vein ; the latter of course are systemic veins. Again, 

 we find corroboration of this view of the parts in Eolis if we 

 look to Doris : here the auricle receives three branches, one from 

 each side, and one from behind as in Eolis ; this last branch in 

 Doris is made up of veinlets from the respiratory organs alone, 

 and hence may properly be called pulmonary or branchio-cardiac; 

 the two lateral branches come not from the special respiratory 

 organ at all, but directly from the skin. Now although the skin 

 in Doris may have in some measure a function like that of the 

 Eolidida, it must from its peculiar nature perform that function 

 in a most imperfect manner ; hence we ought to look upon these 

 lateral venous trunks in a corresponding inverse ratio as systemic 

 veins. Thus both in Doris and in Eolis the blood enters the 

 auricle in a state of only partial aeration, one portion reaching it 

 from the respiratory organ, and another from the general system. 

 In the Crustacea the blood in the great dorsal sinus is in the 

 same state, a fact that John Hunter had long ago ascertained, 

 and Professor Owen has more recently confirmed. Here surely 

 there is not that degradation implied in the idea of Phleben- 

 terism ; and according to M. Milne-Edwards' own showing, the 



