MDREX. / 



ceous character of the spinous parts about the aperture are 

 Tiuich more conspicuous than in the specimen figured. 



26. calcar, f. 35, Kiener. — Testa M. formosce similis sed 

 alba, varicibus multo magis membranaceis. — There is a gra- 

 dation almost complete in the webbed character of the latest 

 varices, between this species and M. formosus, some speci- 

 mens of the latter being almost as much webbed. 



27. senegalensis, f. 29, Gmeliii. — Testa subfusiformis 

 ventricosus, fuscus, spiraliter lirata, inter varices plicato- 

 bituberculata ; varicibus crassis, ad angulum anfractuum uni- 

 spinosis, infra aperturam laminatim fimbriatis, canali brevi 

 lateraliter recurvo, superne unispinoso.— Having something 

 of the motacilla form, and the latest developed varices having 

 a laminated fringe. 



28. nubilus, f. 7l,Sowerby. — Testa M. Senegalensi simili, 

 graciliora, castaneo-trifasciata, canali breviori, trispinoso; 

 varicibus antice baud fimbriatis. — It is possible, but not 

 probable, that this may be a Senegalensis in an early stage of 

 development. It is more fusiform and has no fringe above 

 or upon the canal. 



29. Eossiteei, f. 83, Crosse. — Testa turbinata, flavida, 

 minute scabra, inter varices obscure unituberculata, varicibus 

 crassis, antice breviter spinoso-frondosis ; spina brevissima, 

 anfractibus tribus, depressis, ultimo subgloboso ; canali elon- 

 gate ; apertura subrotunda, prope marginem utrinque rosea, 

 lirato-dentata. — A very aberrant form and difficult to group 

 with any others, unless it be with M. laciniahis, triqueter 

 &c, whose fronds are only developed anteriorly. 



30. motacilla, f. 129, 1 30, Lamarck. — Testa subquadrata, 

 ventricosa, spiraliter lirata, fulva, vel rosea, fusco rubroque 

 fasciata, spiraliter lirata, inter varices plicato-bituberculata ; 

 varicibus costatis, fronte subplanatis, ad angulum breviter 

 unispinosis, infra aperturam fimbriatim spinosis ; canali valde 

 recurvo, attenuate. — The canal in f. 130 is of stunted growth. 

 Several of the following have been taken for this species, 

 which may now be considered as finally determined. 



31. elegans, f. 25, Beck. — Testa solida ventricosa, elavi- 

 formis, tortua, fulva, spiraliter lirata, Kris angustis concinnis 

 rubris, inter varices tuberculo maximo munita, varicibus cras- 

 sis, latis, sublaeviratis ; canali tortuosim recurvo. — Distin- 

 guished from M. motacilla by the neat spiral brown painted 



