370 



AFFECTION TO YOUNG. 



Mollusca. We find also a viviparous species where we should 

 little expect, a priori, to find it, amongst the zoophagous 

 Mollusks that produce concamerated nidi. The Yet (Fig. 

 29, p. 169), or Cymba neptuni is so ; and the shell of the 

 new-born young is an inch long. Adanson found four or 

 five of these in one parent ; and he thinks that the mother 

 nurses them in the first months of their infancy, for he had 

 seen several which carried about their five little ones in the 

 folds of the elephantine foot until the shell of them had 

 reached the length of an inch and a half.* The fragile 

 species of Bulimi, with a simple lip to the shell, are mostly 

 viviparous ; the Partula, a genus allied to Vertigo, is simi- 

 larly conditioned ; and we find other viviparous hermaphro- 

 ditical species in the genus Helix itself. 



Adanson's anecdote of his "Yet" reminds me of some 

 other species which make seemingly an amiable exception 

 to that cold indifference to their ova and young which cha- 

 racterizes the vast majority of the Mollusca. The ancient 

 naturalists indulge in stories of the Cuttlefish hatching their 

 eggs and guarding their nests with jealous care ; and, ac- 

 cording to Aristotle, the female is often to be seen resting 

 against the ground and covering the eggs with her body. 

 The Ocythoe or Argonaut nurtures her eggs in her beautiful 

 shell. f Neritina fluviatilis is said to carry its offspring about 

 on its shell ; and the N. pulligera has got its name from a 

 similar habit ;j but the inferences are probably deduced 

 from some accidental occurrence or from misinterpreted ob- 

 servation^ — as has undoubtedly been done in the case of 

 our common Limpet, when it was found, perchance, seated 

 upon some very little individuals of its own species, — op- 

 pressing and not brooding on them. The Calyptraea affords 

 a less exceptionable example, for this Gasteropod appears 



* Senegal, 48. 



t " Mr. Adams regards the Argonaut shell as a nest formed hy the female 

 to contain her eggs ; if this is correct, it can scarcely be compared to other 

 shells. He regards the shell as similar to the cartilaginous cases which 

 Murices and other zoophagous Mollusca form to contain their eggs ; but it 

 has no apparent analogy to those bodies, which are secreted by the oviduct 

 as the eggs are deposited." — J. E. Gray, Moll. Brit. Mus. 29. See also 

 Edwards' Eocene Mollusca, 7. 



X Blumcnbach's Nat. Hist. 265. 



§ " Grana, quse dorsum cochleae frequenter occupant, esse ipsius Neritse 

 pullos, Rumphius docet ; horum ducenta triginta quinque in uno specimine 

 numeravi, ovalia, convexa, extus luteo-albida, intus alba, moleculis referta, 

 corpuscula hcec srepe absterguntur, remanente in testa circulo ovali albo. 

 Nisi obstaret autoritas exactissimi Rumphii, ovula peregrini animalculi 

 putarem." — Muller, Verm. Terr, et Fluv. ii. 196. 



