1892.] MICROSCOPIOAL JOURNAL. 219 



If the shell has 4 or more joints it is either Eucyrtidimn or 

 Lithocampc aiul the presence of a horn on the cephalis marks 

 the former. 



Next we come to. 3 genera in which the skeleton has 



Two Chambers. 



In these there is neither abdomen nor thorax, only the two- 

 lobed cephalis, and the characteristics are as follows : Pctalos- 

 pyris has one horn, Ceratospyris many, while Cladospyrls has 

 branched or forked spines, or the edges of the appendages are 

 serrated. Ehrenberg figures still other forms without horns or 

 spines, or with only one small horn or short projecting teeth, 

 which he assigns to the genus Dictyospyris^ but llaeckel, if I 

 remember right, makes no mention of any such genus. 



And finally we have 3 genera in which the skeleton has 



Many Lobes or Chambers. 



These are LitJiobotrys and Botryocyrtls and the former may 

 be recognized by the presence of tubes on the cephalis. 

 ( To be continued. ) 



MICROSCOPICAL APPARATUS. 



Edinburgh Student's Microscope. — This instrument, made 

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