390 PEOE. ALLMAN ON THE EBCENT BESEAKCHES 



structureless (fig. 4), or it may present various kinds of structure 

 or sculpture, often very elegant and characteristic (figs. 5, 7). 



The soft protoplasmic contents of the test are in the freshwater 

 Thalamopliora almost always differentiated into a more granular 

 portion and a more homogeneous portion. In those with a single 

 orifice the granular protoplasm lies towards the anterior or oral 

 end, the more homogeneous towards the posterior or aboral end. 

 The posterior homogeneous protoplasm includes the nucleus, 

 while in the anterior granular portion, or on the boundary between 

 the two, lie numerous vacuoles. These are almost always rhythmi- 

 cally contractile, and are constant in number and position in each 

 species. "When there are two shell-orifices the nucleus lies in the 

 middle point between them. In the Arcellcs, which present the 

 condition very exceptional among freshwater Thalamophora of 

 being multinucleate, the nuclei lie in the marginal part of the 

 nearly disk-shaped protoplasm. 



The characteristic form of the nucleus is that of a clear vesicle, 

 which almost always includes a pale bluish nucleolus. 



The pseudopodia present two important modifications. In one 

 (figs. 4 & 5) they are cylindrical, blunt, unbranched, non-confiuent, 

 and usually destitute of granule-currents. In the other (fig. 6) 

 they are very contractile delicate pointed threads, which repeatedly 

 ramify and flow together, and present currents of granules in their 

 interior. Between these two, however, there are numerous inter- 

 mediate conditions, but the two main forms, the blunt and the 

 pointed, may always be distinguished ; and Hertwig and Lesser 

 accordingly employ these characters in the definitions of some of 

 their higher groups, adopting from Carpenter the name of Lohosa, 

 which they assign to the forms with blunt pseudopodia, and assigning 

 that of Bhizopoda to those in which the pseudopodia are poiuted. 



The name of " E-hizopoda," in the special sense in which it is 

 here employed by Hertwig and Lesser, is certainly objectionable, 

 and from its being very generally used with a different significance 

 would tend to introduce confusion into our definitions. E. E. 

 Schulze uses in the same sense the more appropriate designation 

 of " rilifera ;" but Carpenter had long ago employed that of " Ee- 

 ticularia" to indicate those forms whose pseudopodia are long and 

 filiform and tend to unite with one another into a network ( Gro- 

 mia and the so-called Eoraminifera). As forms occur, however, 

 with filiform pseudopodia which show no tendency to anastomose, 

 the designation " Filifera " is of more general application. 



