Additional Notes on the Lily dale Limestone. 159 



of its resemblance to that genus in several particulars, and 

 especially in its having an umbilical cavity extending the whole 

 length of the shell, but as Niso is not elsewhere known to occur 

 as far back as the Upper Silurian, lie suspects that further 

 examination may show it to differ from Niso, and in that case 

 lie proposes to call it Yetotuba. I may mention that I have 

 found several more perfect specimens than the one he figures, 

 demonstrating that which he surmises as possible, a very marked 

 difference to Niso in that the umbilical cavity appears to project 

 below the base of the shell in the form of a short tube, somewhat 

 like the anterior canal of a Cerithium, only straight instead of 

 abruptly turned to one side, and being an extension of the 

 hollow columella, and not a mere prolongation of the mouth. 

 Under these circumstances I prefer to adopt Mr. Etheridge's 

 alternative name Vetotuba. There are at least two species if not 

 more of these turreted shells belonging to the Pyramidellidae. The 

 above remarks apply more especially to the one he figures under 

 name Niso (Vetotuba) Brazieri, and which, as he says, has no more 

 than twelve whorls. T have however in my possession and on view 

 to-night, another species much more slowly tapering and 

 consisting of nearly twenty whorls, but the anterior part is not 

 sufficiently perfect to define it, and so we must wait for a better 

 specimen. Besides this I may mention that there is a small 

 species that has more resemblance to a true Niso. 



