DICECIOUS MOLLUSCA. 361 



pends the ovigerous capsules from its float ! From the 

 float? Yes* the snail is taught to fix its ovigerous cap- 

 sules, which are sometimes numerous, to the under side of 

 the " float," where they are suspended by little pedicles in 

 a line, or after a pattern peculiar to each species. It is said 

 that the mother then detaches the float loaded with its 

 teeming burden ; and suspended, in this way, near the sur- 

 face, the embryo young receive the influence of the life- 

 giving air, and are matured ; and thus the race is preserved 

 and multiplied.f Here you have the pretty fable of the 

 Halcyons almost realised; and in your reflections on the 

 real you may arrive at the old conclusion, that " Heroum 

 fabula veris vincitur historiis." 



All the Cephalopods belong to the dioecious section of 

 mollusca, and the sexes of at least many species are distin- 

 guishable by a marked difference in the form of the body. 

 Risso says that the body of the male Octopus is more conical 

 than that of the female ;J and the distinction is still more 

 marked in the Loligines. The male of Loligo subulata has 

 the extremity of the body prolonged behind by a fleshy tail 

 a half longer than the female ; and as this dissimilarity ex- 

 tends to the cartilaginous pen or back-bone, a naturalist 

 ignorant of the sexual distinction might be led to mistake 

 the sexes for distinct species. The males of the Octopus 

 are also less numerous than the females in the proportion, 

 as estimated by Cuvier, of about five to one ;|| but the 

 grounds on which the estimate is founded are uncertain, 

 nor can it be safely applied to the other genera of Cepha- 

 lopods. 



The Cephalopods are, without any exception, oviparous ; 



* A fact first ascertained by Sir Joseph Banks : " "We also took several 

 of the shell-fishes, or testaceous animals, which are always found floating on 

 the water, particularly the Helix ianthina and violacea ; they are about the 

 size of a snail, and are supported upon the surface of the water by a small 

 cluster of bubbles, which are filled with air, and consist of a tenacious slimy 

 substance that will not easily part with its contents. The animal is ovi- 

 parous, and these bubbles serve also as a nidus for its eggs." SIR JOSEPH 

 BANKS, in Kerr's Collect, of Voyages and Travels, vol. xii. p. 370. edit. 1824. 



t Rang's Manuel, 197, pi. 5, fig. 3. Zool. Journ. iii. 265. Mrs. Gray's 

 Fig. Moll. Anim. i. pi. 48. Sir Everard Home has published a beautiful 

 figure of the shell of an Ianthina covered with a much twisted and beaded 

 filament formed by a long series of membranous capsules or cells, each cell 

 enclosing a single ovum. This Sir Everard unhesitatingly (yet erroneously) 

 describes as the " camerated nidus " of the Ianthina. Comp. Anat. iii. p. 

 398, and iv. pi. 141. 



J L'Europ. Merid. iv. 5. 



Ann. des Sc. Nat. (1842) xviii. 259. 



II Mem. i. 31. 



