MAGI L U S. 



Genus MAGILUS, Montjhrd. 



MoUiiscvm gasteropodum marinum, madrejioricolum. 



Testa (State juniori hdiciformis, tenuis, yauctspiratis, 

 plerumqm extus striis undulatis squainiferis rugata, 

 alba ; spira obtusa, npertura ovata seu pynforiai, 

 ■ caiiali antico distincto ; atate senion in spedehus 

 plurimis viargine aperturcr, in tiibinn eloiujutum, 

 iiTcgularein, incrassaiam. extenso. 



Operculum conieum elongatum, nucleo latendi. 



Mollusc gasteropodous, marine, inhabiting madrepores. 



Shell, in a young state, thin, few-whorled, generally 

 roughened externally with wavy, squaniose striiB, 

 white ; apire obtuse, aperture ovate or ])yriibrm, 

 anterior canal distinct ; in an adult state, in 

 several species, the margin of the ajjcrture ex- 

 tended into an elongated, irregular, thickened 

 tube. 



Synowjma. Caupvlatvs, G'ui'ttanI ; pars LEi'TiKdNi'iii's, 

 Riippell. 



The habits of this genus of in.illus. 

 curious. The young fry, after a short j) 



are very 

 id of free 



locomotion, seems to find its way into some hole in a 

 growing madrepore, and tlien to become stationary ; 

 but as the substance grows round it, it would soon 

 become enclosed unless the growth of the shell kept 

 pace with that of the madrepore. In order, therefore, 

 to keep its aperture close to the surface, the two lips 

 are extended in the same direction in the form of an 

 irregular tube. The magilus leaves its shell in the 

 original cavity, and filling it up so tluit it becomes 

 solid, occupies only that portion of the tube which is 

 nearest to the ojiening. The walls of the tube are 

 thickened, and the portion which represents the canal 

 is consolidated into a thick keel. 



The species which have not been found as yet in an 

 advanced state, and which appear generically to re- 

 semble the young shells of Magilus antiijuus, have been 

 separated by authors under the generic term J.ipta- 

 conchus ; and it is asserted that while the magilus 

 possesses an operculum, the Leptoconchi do not. It is 

 also said that the young shell uf the Magilus begins to 



form a thickened and entire edge to its aperture, as it 

 preparmg for the future erratic course of its .sheU. It 

 appears to me, however, that it depends upon the acci- 

 dental conditions of habitat and growth whether and 

 at what period of life the shell of a Magilus shall become 

 tubular; and as for the operculimi, it is ceruin that 

 some, if not all, the species enumerated as Lepto- 

 concluis by authors have been found with opercula; — 

 notably, we have figured the genuine opercuhuii of 

 LeptoamclMS, L.\M.^iiCKii, Deshayes. 



The Isle of Bourbon, the Mauritius, and the Sand- 

 wich Islands — perhajis most islands with reefs — afford 

 homes to the Magili. 



Species 1. (Fig. 



rf, e, Mus. Brit.) 



Magilus antkjius. Mwj. testa, a-tate jimivri leiiui, 

 gtobosa, spiraliter striata, antici' svbsen-ato-cos- 

 tatd ; longitudinaliter squaiuoso-striatd, spin) 

 plerumque brevissinia, ranati brrri, bdiio interim 

 la'vigatn, rolumelld arrxtatd : hdiio e.r/c.rno /irope 

 canalrm suhcnnlni,'!,, ■ a lair srnian solidd, nigosd, 

 till,,, I.,!,,-.' .xhriK, .-qinim.'su- 1 „:/alo. latere iiitcriia 

 laniiu;.^ irnyalardm. i,icri.,atu. 

 The ANTiQUK Magilus. Shell, in a young state, thin, 

 globose, spirally striated, anteriorly with subser- 

 roid ribs, longitudinally s([uamosely striated, s)iiie 

 generally very short, canal short, inner liji smootli, 

 columella arched; outer lip slightly contracted 

 towards the canal; in the older state solid, ru- 

 gose ; tube squamosely-rugose on the outer side, 



! thickened with lamina; on the inner side. 



1 Lamakck. Anim. sans vert., vol. v. 



I Campiilotus, Guettard. 

 Hab. Ifle of Bourbon. 



Our figure, a, repi 

 specimen of Magilus 



its an luiusually lengthened 

 iiadrepore. /' is a specimen 



Decendx-r, 1872. 



