INFUSORIAL ANIMALCULES. W 



Siebold adopts the genera, but not the families of Ehronberg, and 

 Bujardin devises a temporaiy distribution of Rotatoria, according to 

 theii- varieties of locomotion ; and, including the Tardigrada, thus 

 makes fom- di^dsions : — 1 . Those which live fixed by their posterior 

 extremity. 2. Those having but one mode of locomotion by means 

 of their nbratiie cilia, and which are all swimmers {nageurs.) 

 3. Those which have two sorts of movement, one of crawling 

 {rampants) after the manner of leeches, the other of s^^'imming, like 

 the preWous forms. 4. Those destitute of vibratile cilia, but provided 

 with aculei or claws (ouglcs) and which are true creepers {marcheurs). 



The last di%'ision {marcheurs) has but one family viz. Tardigrada ; 

 the third but one also, viz. — Rotifera ; the first two families, the 

 Floscuhriens and Melicertiens ; whilst the second is separable into 

 two sections, Brachioniens and Furciihn'ens, each i-epresenting nume- 

 rous genera. 



Owing to the absence of silica or lime in the integument of Rota- 

 toria, and its consequently perishable nature, these animals do not 

 occur in a fossil state. 



The Rotatoria are distributed over every part of the world ; the 

 special or Kmited geographical distribution of genera, we have, at 

 present, no data to determine. 



Section XXYI. — On Shoivers of Infusorial Animalcules. — In 

 ancient and modern times, storms or showei'S of solid bodies ha"\'e 

 occasionally been observed. The dust which falls upon the earth, 

 when of a red colour, has been compared to blood ; and in Egypt, 

 where little or no rain falls, the superstitious inhabitants have been 

 much alarmed when such an event has happened. Professor Ehrcnberg, 

 in a work now before me, entitled Passat- Staub und Blut-Regen, 

 referi'ed to at page 65, has, with the characteristic energy and per- 

 severance of his countiy, investigated this subject veiy minutely, 

 and I propose here, to give some of the results of his research. 



The memoir occupies 192 folio pages besides tables, and is accom- 

 panied by six large plates. 



The quantity of actual solid matter that has fallen fi'om the atmo- 

 sphere by showers, is far more considerable than might be imagined, 

 for though it falls in a divided dust-like mass, the extent of surface 

 which it covers is large. Comparing it with Meteorilites, Ehrenberg 



H 



