iy PREFACE. 



favourable reception of the first has induced me to pre- 

 pare the present manual, conceiving greater benefit would 

 accrue to science by reconstructing it, and introducing 

 the discoveries made since that time, than by a mere 



reprint. 



Dr. Ehrenberg's magnificent and elaborate work, entitled 

 Die Infusionsthierchen, having since appeared, and offering 

 a better classification than Miiller's, it has been adopted 

 here. I have only to regret that its distinguished Author, 

 or some more competent Naturalist than myself, has not 

 presented us with an epitome of it. 



In the description of the families, genera, and species, 

 I have not adhered to Die Infusionsthierchen, but only 

 condensed such portions as appeared desirable, inter- 

 weaving them with other matter : hence it would be 

 unjust to its Author to consider this manual an abstract 

 of it. That work being intended to establish a new 

 classification, and as a book of reference, a large jDortion 

 of its ample 600 folio pages is occupied in giving the 

 synonyms, in references, and in discussions ; these I 

 have- omitted, but every species described in that work 

 will be found here, together with many others since 

 discovered. 



A new system of classification is seldom acceded to 



