PRACTICAL MICROSCOPY. 



show that the Diatomaceae are, and have been, very widely 

 distributed. 



Some collectors may consider the pocket microscope 

 shown in Fig. 123 not steady enough for general use, and 

 therefore may prefer the form shown in Fig. 124 as made 



FIG. 124. 



by Mr. Browning and others ; it is exceedingly portable 

 and very steady, as the author can testify from its practical 

 use when travelling in North Wales. 



Amongst the diatoms which may be singled out for 

 examination are Pleurosigma angulatum (Fig. no), P. 

 formosum (Fig. 109), Navicula firma (Fig. 125), N. lyra 

 (Fig. 126), N. rhomboides (Fig. in), Isthmia enervis, 

 Arachnoidiscus Ekrenbergii, Meridian circular e y Diatoma 

 vulgare, and a host of others. 



Whilst writing this chapter the author has received a 

 tube of diatoms from Mr. Bolton of Birmingham, consist- 

 ing of a number of species found attached to algae in the 

 canal of that neighbourhood ; the most easily recognised 



