234 



OjST the topography akd geology 



V 



S. gigas. Linn., Syst. Nat. (12 Ed.) p. 1310. . . ■ . 



Two or three good characteristic specimens found. 7 



ORTHAULA.X. Gabb, w. gen. 



Shell rounded-fusiform, canal moderate, straight and regularly tapering, adult shell enveloped over the whole 

 spire by an extension of the inner liji, posterior canal fissure-like, formed by the continued edge of the outer lip ai-d 

 running directly to the apex. Outer lip apparently shari) and simple, anterior notch oblique and broad. 



The discovery of this genus tills an important break in the Rostellarias, uniting 

 "*^the true genus, Rostellaria with Conrad's Calyptrophorus. Unlike both of these 

 genera the canal is not styliform, but robust and comparatively short, and its terminal 

 notch is foi'med by an almost rectangular truncation of the anterior portion of the 

 outer lip. Like Bostellaria, it has a straight posterior canal, prolonged hov/ever, 

 further than is common in that genus. The canal is similar in structure to that of 

 Calyptroi^liorus, being formed by a squamose plate; 1)ut in the latter genus it curves 

 over backwards, behind the spire, wdiich it ascends to about half its height and then 

 bends down to near the sutiu'e of the body whoib Unlike the first, and like the 

 second of its congeners, it has the whole spire enve]oi)ed in a plate which should more 

 properly be described as a posterior extension of the body whorl, carrying the suture 

 to the extreme apex. The lines of growth run from the top of the spire to anterior end 

 of the shell. It carries none of the tubercles seen in Calyjjtroplwrus and Tessarolax, 

 and seems, unlike most of the other genera of the family, to have had a simple outer 

 lip, neither digitate nor notched. . . _ 



O. inornatus. Gabb, n. s. ' ■ ' 



Shell broadly rounded-fusiforin. Young shell w ith the spire a little shorter than the aperture, suture impressed, 

 whorls numerous, nuclear whorls three, the subsequent ones showing faint traces of occasional thickenings disposed 

 like the varices of Triton ; surface smooth ; anterior end of body whorl marked by a few faint revolving lines, no 

 posterior canal. Adult shell more distinctly fusiform, the spire covered by a longitudinally striated incrustation 

 covering the sutures and extending to the extreme apex. Aperture elongated, acute behind and prolonged into a very 

 narrow posterior canal running straight to the apex ; in advance it is gradually narrowed, the anterior notch broad and 

 shallow ; inner li}! thinly cncrus'-.cd ; outer li^) thin in all my specimens, and apparently thin, straight and entire in the 

 perfect adult. Size of largest specimen, length 3.75 inch, width 1.5 inch. 



DOLOPIIANES. Gahh, n. fjen. 



Shell elongate oval, spire elevated ; showing a minute imperforate umbilicus ; aperture semi-oval ; inner lip 

 slightly encrusted, outer lip acute, sinuous ; anterior end of the aperture terminating in a short, not emarginate canal. 



The first impression produced on looking at this little shell is that it is probably 

 a Melania ; but apart from all of its three liundred associates being marine, which 

 Avould render such a I'eference improbable, it has a grouping of characters which ally 

 it so closely to Striitiiiolaria, that I am convinced that it is most probably a nearly 

 related genus. Its spire is very like that of many species of Stromtidce and, in the 

 details of its mouth it differs from Strutliiolaria in having a thinly encrusted inner 



