36 MICROSCOPICAL OBJECTS FOUND 



this memoir with sketches of some of the most 

 characteristic forms. 



One of the most abundant is represented by 

 fig. 27, which I am unable, in its young state, to 

 distinguish from Rotalia stigma, of Ehrenberg, but 

 which I believe to be Rosalina globularis, of D'Or- 

 bigny . Its outer shell exhibits large and well marked 

 foramina, and through which the pseudopodia have 

 been projected.* Fig. 29 represents the soft 

 animal dried up, and, by some fortunate accident, 

 deprived of its calcareous covering, forming an 

 admirable illustration of the peculiar structure 

 so well described by Ehrenberg. Since disco- 

 vering the above, I have succeeded in obtaining 

 other specimens, after destroying the calcareous 

 portion, by means of a weak solution of hydro- 



* This and several of the other objects have been repre- 

 sented as they appear after they have been rendered trans- 

 parent bjf transmitted Hght. We thus obtain a view analo- 

 gous to what would be afforded by a section — the only way 

 in which we can study their internal structure. At the same 

 time the plan is very unfavourable to the identification of 

 species, and sometimes even genera, though it is the one 

 adopted by M. Ehrenberg. M. D'Orbigny, on the other 

 hand, always examines them with condensed light as opaque 

 objects — the only way in which the species can be determined, 

 with any degree of certainty. 



