ANDROGYNOUS MOLLUSCA. 363 



III. HERMAPHRODITICAL MOLLUSCA. 



It is a common remark that the most improbable fictions 

 of the novelist meet their counterparts in the romance of 

 real life ; and it may be said with at least equal truth, that 

 the wild creations of the poet find themselves realized among 

 the structures of organised beings. Invention has not gone 

 beyond what is actuated. Men who carried their heads 

 under the shoulder are not more eccentric than the creatures 

 which carry their legs and arms on their head ; and we can 

 instance whole tribes of animals rivalling the nations which 

 were feigned to have their mouths in the breast. When the 

 poet sang the metamorphosis of Hermaphroditus and Sal- 

 macis, and incorporated them in one, he imaged a monster 

 which finds indeed no parallel in higher organisms ; but 

 amongst the Mollusks there are hundreds which, if known 

 to him, might have suggested arid almost justified the fancy. 

 " Beyond those Nasamones," says Pliny, " and their neigh- 

 bours confining upon them (the Machlyes) there be found 

 ordinarily Hermaphrodites, called Androgyni, of a double 

 nature, and resembling both sexes, male and female, who 

 have carnal knowledge one of another interchangeably by 

 turns, as Calliphanes reports."* An exact description this of 

 some tribes of mollusks which border on the dioecious Gas- 

 teropods. John Ray discovered, in the gardens of Cam- 

 bridge, that the common snail was of the nation of the 

 Androgyni, male and female, every individual having the 

 peculiar organs of both sexes. Subsequent researches have 

 shown that this structural union prevails, with a very few 

 exceptions, in all the land and fresh-water snails which 

 breathe the air uncombined, in all the nudibranchial Gas- 

 teropods, in the Inferobranches and Tectibranches, and in 

 the Pteropods, together constituting a very considerable 

 section of the Mollusca. But although really bisexual, it is 

 also true that no individual of these many tribes can im- 

 pregnate itself; the union of at least two individuals is 

 necessary for the propagation of the species : and it is 

 asserted that though either of the two can act the part of 

 the male or of the female, yet that one of them only is made 

 pregnant from one union. I have said that at least two 

 individuals are required to unite, and you may notice with 

 surprise the limitation, and probably deem the phrase a 

 mere pleonasm, but it is not so. In the lacustrine pulmo- 

 nated Mollusca, represented by the Limneus and Planorbis, 



* Holland's Plinie, i. 154. 



