360 DKECIOUS MOLLUSCA. 



ing-cards.* "They are compressed pouches, nearly of the 

 size of a silver penny, supported on a very short pedicle, 

 and opening on the top to give a doorway to their embryos, 

 You may remember that some Mollusks which have an 

 entire, and not a channeled or notched, aperture to the 

 shell, are nevertheless zoophagous ; and these further evi- 

 dence their resiliancy from the phytivorous families, with 

 which they have too long been associated, by the character 

 of their egg-repositories. It is true these cannot well be 

 reduced to any of M. Lund's classes, but they are conca- 

 merated nidi of a peculiar character. The Naticse afford 

 examples. Their egg-receptacles were long believed to be 

 a zoophyte, although Ellis's knowledge prevented him from 

 participating in the mistake : the mass appeared to him " to 

 be a collection of sand, united by the viscid matter of some 

 sea-insects, and disposed in a flat thin surface, full of small 

 cavities, where the insects have been."f Its true nature 

 seems to have been first suspected by Mr. Boys, and fully 

 demonstrated by Mr. J. Hogg by hatching the young of a 

 pretty Natica found on the English coast. Dr. Gould thus 

 describes the nidus : " It is a mass of sand glued together 

 into the shape of a broad bowl, open at the bottom, and 

 broken at one side. Its thickness is about that of an orange- 

 peel, easily bent without breaking when damp, and when 

 held up to the light will be found to be filled with little 

 cells arranged in quincunx order. Each of these cells con- 

 tains a gelatinous egg, having a yellow nucleus, which is the 

 embryo shell. It is found plentifully at Midsummer on every 

 sandy flat where any species of Natica resorts." J Yes ! the 

 Natica has a sand wherein to bury for a time its germinating 

 young, but where is the oceanic lanthina to secure its pro- 

 creant nest that it may not be, like the weed, cast away 

 where'er the rude imperious surge may prevail ? It sus- 



doubt, Ellis says, " So that we may properly look upon this sea-cup as the 

 ovary to the Periwinkle shell-fish ; " but the name was indubitably not 

 restricted by Ellis to the Littorina, being used, as defined by Johnson, to 

 designate "a small shell-fish." Many of the fishermen in my neighbour- 

 hood still so apply the name to the Purpura lapillus, and Ellis's figure 

 proves he knew the nidus to belong to this species. Lund was, however, 

 ignorant of the fact. I knew the relation between the shell and cup so 

 early as 1815, and my impression is, that my knowledge of it was derived, 

 not from personal observation, but from my honoured teacher Professor 

 Jameson of Edinburgh. 



* Report Brit. Assoc. 1843, p. 129. Ann. and Mag. Nat. Hist. xiii. 204. 

 The ova capsules of Fusus norvegicus and F. turtoni resemble this in sim- 

 plicity. Howse in Ann. and Mag. Nat. Hist, xix, 162, pi. 10, fig. 3 and 9. 



t Corallines, 74. 



j Invert. Massachusets, 232. 



