A REVISION OF TH13 GENUS STEGANOPORELLA. 241 



for further examination, while the opercula are placed in a 

 test-tube with nitric acid (which should not exceed about 50 

 per cent.) and boiled for two or three minutes. I have found 

 this procedure specially necessary in the case of dry speci- 

 mens, in which the dried tissues in connection Avith the 

 orifice are by no means easy to remove from the lower side 

 of the opercula. Even after treatment with nitric acid it is 

 often necessary to brush or dissect away these remains, in 

 order to obtain clean preparations of the opercula, which are 

 mounted in Canada balsam after staining with picric acid. 

 If the material is not specially valuable the opercula may be 

 prepared by boiling the dry fragment of a colony in nitric 

 acid ; but the other method is preferable, in that it permits 

 the examination of the dry calcareous parts and of the 

 opercula of the same fragment. In dry mounts of specimens 

 from which the epitheca has not been removed some in- 

 formation with regard to the characters of the calcareous 

 parts may be obtained by wetting the epitheca, a procedure 

 which makes it for the time more transparent. 



The examination of the calcareous parts could hardly have 

 been made except by employing some device for rotating the 

 fragment, so as to be able to see it from different points of 

 view. I have used for this purpose a small cylinder, as 

 described in my paper on Lichenopora,^ to which the piece 

 of the colony could be temporarily fixed. 



Steganoporella, Smitt (Steginoporella, Smitt, 1873). 



Zoarium encrusting, Hemescharan or Escharan. Zooecia 

 typically dimorphic, completely covered in front by a mem- 

 branous epitheca, the oral region alone rising as a calcareous 

 arch above its level. Opercula of great size, rarely less than 

 320 fi in diameter, and often much larger, strengthened by a 

 girder (main sclerite) which projects from the lower surface, 

 and often by additional girders. Cryptocyst a more or less 

 horizontal, porous plate proximally, separated from the 

 epitheca by the depth of a tubercular calcareous shelf; 

 ' ' Quart. Jouru. Micr. Sci.,' xxxix, 1897, p. 74. 



