98 MONODONTA. 



Hutton and others is a distinct species. A notable character of this 

 species is the band of iridescent nacre which connects the termina- 

 tions of the peristome, extending across the parietal wall. 



M. CRUSOEANA Pilsbry. PI. 35, figs. 19-21. 



Shell similar in form to M. nigerrima or somewhat more depressed ; 

 the color, columella and parietal wall as in M. nigerrima ; Outside 

 closely conspicKously spirally Urate, the sutures bordered below by a 

 depression or groove ; outer lip acute, thin, very narrowly black- 

 edged, bordered within by a broad band of very thin white sub- 

 stance, which overlies the nacre ; parietal wall with a band of nacre 

 connecting the ends of the peristome, but obscured by the same thin 

 opaque layer; fauces brilliantly iridescent ; lip lirate within ; upper 

 angle of the aperture narrowly channeled ; ribs of the outer surface 

 about 8 in number on the penultimate, 20 (more or less) on the 

 last whorl. Alt. 15, diam. 17 mill. 



Ins. Jtum Fernandez ; Coqniiiibo, Chili. 

 Two travs of this well-marked form are before me. It is need- 

 less to compare with the Australo-Zealandic species, for the band of 

 nacre across the parieto-cohunellar region, connecting the termina- 

 tions of the peristome, at once separates our species from these, and 

 allies it to M. nigerrima, the only other form exhibiting this char- 

 acter. From M. nigerrima it is separated by the much stronger 

 liration of the entire surface, and the canaliculation of the sutures. 



Section Neodiloma Fischer,- 1885. 



Neodiloma Fischer, ]Manuel de Conchyliologie, p. 820. 



Differs from typical Diloma principally in its Australasian dis- 

 tribution. The dentition also differs somewhat from Diloma. (PI. 

 50, fig. 12, Neodiloma cethiops Gmel.) 



M. .ETHiOPS Gmelin. PL 19, figs. 99, 100 ; pi. 20, fig. 19. 



« 



Shell imperforate, globose-conoid, solid, thick, blackish, encircled 

 by series of narrow white marks, formed by the interruption of nu- 

 merous longitudinal white lines by narrow spiral black stripes ; spire 

 conic, whorls 5, convex, the first eroded, spirally sulcate, the last 

 marked by narrow, separated spiral grooves, the cuticle lamellose- 

 striate ; base convex, eroded and subconcave in front of the aperture ; 

 aperture large, oblique, expanded ; outer lip black-edged, then thick- 

 ened with opacpie white ; columella short, obtusely bidentate, the 



