406 PBOF, i.LLMAN ON THE RECENT EESEABCHES 



spherical form ; and in all the specimens examined its contents 

 consist of minute granules which by their strong refringency 

 render the whole dark and opaque, and make an exact know- 

 ledge of the contents of the cyst impossible, though a lighter 

 central portion, probably a nucleus, can be distinguished from a 

 darker cortical portion. The cyst consists of a nitrogenous mem- 

 brane, and has a finely punctured structure; it is connected - 

 with the narrow end of its closed investing shell by a thin solid 

 homogeneous cord. The formation of the cyst and its investing 

 shell is accompanied by the closure of the outer shell-orifice by a 

 temporary plug formed by foreign bodies, such as filaments of 

 Algae and shells of Diatoms. 



Hertwig and Lesser regard all this as nothing more than an 

 example of the encysting process so widely distributed among the 

 Hhizopoda, and whose original object consisted most probably in 

 protection against the evil consequences of the drying up of the 

 surrounding water, but which in many cases has become further 

 subservient to a multiplication by self-division of the protoplasm. 



The genus Cyphoderia was founded by Schumberger for a beau- 

 tiful little monothalamian rhizopod which he obtained from fresh 

 water in the Yosges and in the Jura, and described under the 

 name of C. margaritacea. This is the same rhizopod which Max 

 Schultze found in the Baltic, and to which he assigned the name 

 of Lagynis haltica. It has been most recently studied by Hertwig 

 and Lesser and by F. E. Schulze. It is remarkable for the ele- 

 gant form of its shell, which, instead of being oval, as in Eugly- 

 pJia, has its anterior end produced into a short curved neck so as 

 to give to the shell somewhat the form of a retort. The shell- 

 structure resembles that of EuglypJia except in the smallness of 

 its component plates and the absence of distinct serration at the 

 orifice. The contractile vacuoles are in the anterior region of 

 the protoplasm, instead of lying, as in EuglypJia, on an equatorial 

 plane between the anterior and posterior. 



F. E. Schulze has obtained this rhizopod from very different 

 localities, and from both fresh, salt, and brackish water. He 

 finds the posterior part of the shell often containing only water, 

 through which bands of protoplasm pass from the soft body to the 

 shell-walls. In the midst of the thick posterior part of the body 

 is always a large, clear, spherical nucleus in which one or more 

 dark roundish nucleoli can be demonstrated. The pseudopodia 

 are destitute of granules, divide at acute angles, run out into fine 



