Prof. G. J. Allman on the Anatomy 0/ Actseon. 157 



and terminating in culs-de-sac, where doubtless resides the func- 

 tion 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 culs-de-sac 

 accurately disentangled ; we have in fact in the Phlehenteric sy- 

 stem of M. de Quatrefages nothing more or less than an unra- 

 veled liver. 



This view of the subject would appear to be admitted to a cer- 

 tain extent even by M. de Quatrefages himself, who describes the 

 blind terminations of the branches as surrounded with a layer of 

 a peculiar substance which he believes to be the liver. Of the 

 connexion of this substance with the gastric ramifications I can- 

 not speak, as in Actceon I could find nothing of the kind. As 

 M. de Quatrefages however has not succeeded in isolating it from 

 the culs-de-sac, his statement amounts to an admission that on 

 these terminations of the branches devolves the function of secre- 

 ting the bile*. 



To the view now taken it may be objected, that the biliary 

 ducts ought to open into the intestine behind the stomach. In- 

 stances however of the bile being poured into the stomach itself 

 are by no means without example among the Gasteropoda, and 

 in some cases, as in Scyllcsa and Onchidiunij this secretion is 

 discharged into the oesophagus. The remarkable partition of the 

 liver in Onchidium moreover is an evident approach to the con- 

 dition assumed by this organ in the moUusca now under consi- 

 deration. Another objection to the hepatic character of the gas- 

 tric ramifications may be urged from the curious discovery by 

 Messrs. Alder and Hancock, that in Eolis the extremities of the 

 ramuli are not really cseca, but open externally through the ter- 

 minations of the branchial papillse. This however cannot be con- 

 sidered as a valid objection. It is true that the termination of 

 the ducts in culs-de-sac has been described as a universal con- 

 dition of glandular structure, but it has been by no means proved 

 that a perforate state of the terminations of these tubes is incon- 

 sistent with the performance of the secreting function. The pur- 

 pose served by this curious condition of the organ in Eolis it is 

 not very easy to explain. I cannot however avoid looking upon 

 the perforations in the extremities of the branchial papillse as 

 analogous to the orifice placed at the base of the branchial plume 



* I have just seen an excellent paper on the anatomy of Eolis by Messrs. 

 Hancock and Embleton (Annals, xv. pp. 1, 77), in which these gentlemen 

 describe the terminations of the gastric ramifications in Eolis as lined by 

 glandular structure, which in most species exhibits a complex follicular dis- 

 position. The caeca in Actceon are certainly much more simple, nor do they 

 seem to be furnished with any distinct glandular lining. 



