Messrs. Alder and Hancock on the genus Eolidina. 127 



How then does M. de Quatrefages consider that the excrement 

 is disposed of in Eolidina ? If we understand him rightly, he has 

 recourse to the idea that it is voided again by the mouth, as in 

 some of the Radiata and Zoophytes. Is not such a supposition 

 contrary to all analogy in an animal so highly organized as this 

 mollusk ? And is it not, we would ask, much more probable that 

 M. de Quatrefages has overlooked the true intestine and anus, 

 which, from the minuteness of the subject and the delicacy of its 

 tissues, are difficult to detect, than that such an anomaly in orga- 

 nization should exist ? That we admit the possibility of a pos- 

 terior dorsal anus in this family will be seen in our description of 

 Proctonotus, in which such an arrangement is found ; and we 

 have since been favoured by a friend with the examination of an 

 undescribed animal of this family belonging to a new genus which 

 has a similar post-dorsal vent ; but in both instances, this part, 

 which is prominent and tubular, we believe to be a true anus, 

 connected with the intestine, and not an appendage to the gastro- 

 vascular system. In the animal observed by M. Milne Edwards 

 it is probably the same. 



The other point of anatomy which we dispute is the absence 

 of a male intromittent organ in the generative apparatus, and the 

 consequent androgenous mode of reproduction, widely different 

 from that of the family to which it belongs. Here again we think 

 that M. de Quatrefages has overlooked the part in question. We 

 observe that he has also failed to discover this organ in his genus 

 Zephyrina, and considers that circumstance a proof of the cor- 

 rectness of his observation in Eolidina. In another place he ex- 

 presses an opinion that his Zephyrina is the same as our Venilia 

 {Proctonotus), in which we are inclined to agree, though, from the 

 vagueness of his description of the former, we are unable to say 

 so with certainty*. 



the papillae as there described. The contents of the ovate vesicle at the ex- 

 tremity of the papillae are in most cases distinctly visible, and its action 

 during the expulsion of the minute bodies is not at all obscure. When this 

 takes place the sides of the vesicle are drawn towards each other, and the 

 extremity, becoming tubular, is thrust into the very tip of the papilla where 

 the orifice is placed. This action is generally repeated several times ; each 

 effort forcing the contents nearer the orifice, through which masses of small 

 elliptical bodies are ejected at intervals with considerable violence, and oc- 

 casionally to some distance. This certainly is very unlike disaggregation or 

 diffluence from pressure, by which M. de Quatrefages supposes we may have 

 been deceived. We used however during these examinations so little pressure 

 that the papillae could move freely about, and in one instance the animal 

 crawled from one side of the compressor to the other while we were exami- 

 ning it. 



* In the generic character of Zephyrina, as given by M. de Quatrefages, 

 there is nothing to distinguish it from Eolis, excepting that it has respira- 



