67 



ribs and spiral grooves. Only one specimen has the aperture quite 



developed and seems to be adult , in the other specimens the 



outer margin of the aperture is thin , the canal less finished. 



Though the generic characters of the groups , forming the large 



Genus Potamides in Fischer's Manual, are sometimes rather un- U 



certain , I think this shell should be considered as belonging to " 



the subgenus or Genus Cerithidea. I have the pleasure of naming 



it after its discoverer. 



