315 



but as the Bivonite can hardly be discriminated from the Petalo- 

 conchi by external characters, it seemed presumptuous to attempt a 

 uuion. Shell external]y closely allied to B. subcaneellata, Phil., 

 from wbich it is principally known by the smaller size and stronger 

 sculpture. Internally it mest lesembles P. cocklidium, from which 

 it may be distinguished by the absence of keels ou the upper lamina 

 during a large part of the length ; and by the geueral absence of the 

 third plait, which, when it appears, is likę another fold of the lower 

 lamina in the šame direction. 



B. Laminis a parietibtia procedentibus. 



4. Petaloconchus varians?, D'Orb. (fig. 4.) 



? An Vermetus varians, B. M. Cat. D'Orb. Moli. p. 47. no. 405. 

 P. t. nUjro-fiisca, irregulariter spirali ; scutptiira rugis spiralibus 

 et rugulis transversis, plerumque haud valde escpressis, vari- 

 ante / intus anjr. plurimis plicis solum instructa ; in medio 

 laminis duabus tenuibus a parietibus superiore et inferiore, 

 parte axin versus, arcuatim procedentibus, ceąualibus, haud 

 valde approximatis, rarius extus reflexis ; plica columellari 

 centrali parva ; pagi7ia interna maxime nitente. 

 Diam. spirae -3, aperturae -08 poli. 



Hab. St. Yincent's,W. I. (TF.B.Carpenter) ; Hondūras (Dysora) • 

 "orsizils {D' Orbigny). 



As far as can be judged frora a partial examination of D'Orbigny's 

 type specimen, this is bis Vermetus varians, in which Dr, Gray 

 found two opercula " orbicular, thin, nucleus centrai ; " apparently 

 paucispiral, likę that of Serpidorbis made nearly flat. At the šame 

 time lt is not safe to speak of shells of this genus without an exa- 

 mmatiou of the \vhole length. The lamina appear to degenerate 

 mto plaits during the principai part of their growth, but when deve- 

 loped closely approximate the next species. 



5. Petaloconchus renisectus, n. s. (fig. 5.) 



P. t. irregulariter spirali, axilata, nigrofusca; anfractibus rugis 

 spiralibus et mgidis transversis, seepe ad intersectiones nodosis, 

 varie ornatis ; laminis per anfr. plurimos continuis, duabus] 

 aąuahbus, tenuioribus, a parietibus, parte axin versus, proceden- 

 tibus, arcuatim medium versus continuis, interstitiohaud parvo, 

 extus, labrum versus carinatis ; camera externa majore, reni- 

 formi; plica una centrali, columellari. 



Diam. spirse -4, aperturae -1 poli. 



Hab. In Oceano ? Indico. IVIus. Cuming. 



Variat (a) t. eleganter rugis spiralibus nodosa. 



Variat (b) quoque sciūptura pcene obsoleta. 



Hab. In Insulis Philippinarum ; legit H. Cuming. 



The species is described frora a large group of very regular growth 

 of which the accretions warrant its being supposed East Indian! 

 Specimens from the Philippinesalso appear notseparable specifically! 



