CHAPTER VIII. 



A Group of Minute SheIvLS — Why Mentioned — The 

 Chemnitzias, or Minute Spire-Shells — The Best 

 Way to Determine Such Specimens — The Odosto- 



MIAS AND THE ObELISK-ShELL — ThE CALIFORNIA CONE 

 — MiTROMORPHA AND MANGELIA — SHELLS MARKED 



BY A Notch in the Outer IvIp — Our Rarest Shell. 



WB are now to consider a group of shells, several 

 of which are so very small that they would 

 scarcely be noticed by any one who was not looking 

 sharply for just such specimens. 



But though they are so very minute, still there 

 are two reasons why I wish to mention most of 

 them ; first, that the shells may be recognized from 

 the descriptions, so far as possible; and secondly, that 

 names which are already known may be compared 

 with what is here said of the species, that thus they 

 may be verified. 



The first species of these little mollusks is named 

 Chemnitsia torqiiata^ Gld., Chem-nitz'-i-a tor-qua'-ta, 

 showing clearly that names and dimensions do not 

 necessarily agree. 



The shell is so small that it would scarcely be no- 

 ticed, yet when examined under the microscope it is 

 very beautiful. 



It consists of a very slender, many-whorled spire, 

 with deep sutures and numerous and delicate cross- 

 ribs. Its color is white, and the whole length of the 

 shell is less than a quarter of an inch. 



