10 FEESH-WATEE EHIZOPODS OF NOETH AMEEICA. 



of M. D'Orbigny that the place of these organisms might be among the 

 lowest instead of among the highest of the Invertebrata." 



The true nature of the Foraminifera, and their relationship with 

 Amoeba, Difflugia, and other animals of the kind, was first recognized by 

 the accurate observer M. Dujardin. 



In the Annales des Sciences Naturelles for 1835, there are two 

 articles from M. Dujardin, entitled " New Observations on the Micro- 

 scopic Cephalopods" and "New Observations on the pretended Micro- 

 scopic Cephalopods". The author remarks that he has observed several 

 genera of these animals from the Mediterranean in a living condition, nota- 

 bly Miliola, Rotalia, etc. The segments of the shell successively augment 

 in volume, and are occupied with a red or orange-colored animal matter, of 

 the consistence of thick mucus, very contractile, and susceptible of length- 

 ening into threads. In conclusion, the author remarks that "if one wishes 

 to assign to these animals their place in the animal kingdom, in considering 

 the absence of organs, the homogeneity and simplicity of their material — 

 a sort of mucus endowed with spontaneous movement and contractility — 

 one is led to place them in the lowest rank I first designated them under 

 the name of Symplectomeres, only having in view the succession of similar 

 parts rolled together, in the known species ; but the observation of Gromia 

 has led me to prefer the name Rhizopods, to express their singular mode of 

 creeping by means of threads, which extend and branch like roots." 



Dr. Carpenter divides the Foraminifera into two suborders: the Imper- 

 forate and the Perforata, founded on the circumstances that in the former 

 the shell has mostly but a single orifice of communication with the exterior 

 for the emission of the pseudopods, while in the latter the shell has its outer 

 walls everywhere minutely perforated for the same purpose 



The sarcode of the Foraminifera consists of a viscid protoplasm, usu- 

 ally more or less colored yellowish, brown, or red ; the color being deepest 

 in the earlier formed chambers of the shell, and becoming less towards the 

 last one, in which it is very feeble or absent altogether. The protoplasm 

 contains granular matter, and vacuoles, or drops of more liquid matter than 

 that of the general mass of the sarcode. Nuclei have commonly been sup- 

 posed to be absent, but recent researches of Hertwig* and Schulzef have 

 proved their existence. The pseudopods of the Foraminifera extend as 



*Jenaische Zeitscbriff, x, 1876,41. tArchiv f. Mikvos. Anat. 1877,9. 



