1892.] MICROSCOPICAL JOURNAL. 219 



If the shell has 4. or more joints it is either Eticyrtidium or 

 Lithocavipc and 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 : Petalos- 

 pyris has one horn, Ccratospyris many, while Cladospyris 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 Haeckel, if I 

 remember right, makes no mention of any such genus. 



And finally we have 2 genera in which the skeleton has 



Many Loues or Chambers. 



These are LitJiobotrys and Botryocyrtis and the former may 

 be recognized by the presence of tubes on the cephalis. 

 {^To be co7itinued.) 



MICROSCOPICAL APPARATUS. 



Edinburgh Student's Microscope. — This instrument, made 

 by ISIessrs. W. Watson & Sons of London, England, is exactly 

 identical in all working parts with the well-known Edinburgh 

 Student's Microscope, except that it is mounted on a tripod form 

 of foot as illustrated in the frontispiece. The Continental or 

 horseshoe pattern is exceedingly popular, and is invariably pre- 

 ferrred by and recommended to students, a^s, owing to its com- 

 pactness, the instrument is rendered extremely portable, but it is 

 not so perfectly rigid in all positions to which the instrument may 

 be inclined for working (especially if the table on which it is 

 placed has inequalities of surface) as the tripod form of foot. 

 This latter is strongly recommended by eminent microscopists, 

 including Dr. Dallinger and Messrs. E. M. Nelson and Andrew 

 Pringle. It undoubtedly gives the maximum of rigidity, and has 

 a very commanding appearance. 



This microscope is strongly recommended for photomicro- 

 graphic purposes, and, owing to the perfection of all the adjust- 

 ments, especially the fine adjustment, the highest powers may be 

 used and the most delicate research conducted with it. The 

 workmanship throughout is of the very finest quality, and for 

 convenience of design the instrument is unsurpassed. 



The following are some of the special features of the instru- 

 ment : 



