78 W. ARCHER. 



contractility on the other ; between such most varied inter- 

 mediate conditions occur, or these characteristics may be 

 combined in the most manifold but seemingly ever charac- 

 teristic, manner. Still they all readily enough fall under 

 one or other of the two great categories designated as Rhizo- 

 podous and Lobose. 



As to reproduction — simple division formation of zoospores, 

 and encysting have been observed. 



The unexpected and very interesting discovery of the 

 Foraminifera being nucleated Sarcodina, made simultaneously 

 by Professors E. Schulze and R. Hertwig — an abstract of 

 whose recent papers is given in another part of the current 

 number of this Journal (which see) — imparts afresh interest 

 to our freshwater Monothalamla, which are thus shown to 

 have a direct relationship to the marine forms through 

 Gromia, &c. ; they are, in fact, Imperforate Thalamophora. 



Monothalamia Monostomata. 



In the discrimination of subgroups no characteristics are 

 seemingly more important than those presented by the pseudo- 

 podia, but those possessed by the test as regards its structure 

 and its figure are of considerable value, in some forms more so 

 than in others — the structure being more of generic, the 

 figure more of specific importance. 



The test itself may be discoid, cylindrical^ or flask-shaped, 

 whilst the monaxial fundamental form may be further deve- 

 loped to a bilaterally symmetrical one, which modification 

 may be brought about according to one or other of these modes : 



(1) An axis vertically transverse to the " longitudinal" 

 may surpass the rest in growth so that the test becomes 

 broader in this direction, and hence laterally compressed 

 (thus Plagiophrys scutiformis , Hertwig et Lesser, with 

 its smooth test, or Eicglypha comprcssa, Carter, with a test 

 formed of superimposed imbricated plates). 



(2) That portion of the test terminating in the " mouth" 

 grows to one side, which thereby comes to lie more or less 

 lateral. (Thus 3Iicrogro7)ita socialis (Arch.), Hertwig, with 

 a smooth test, or Cyphoderia margaritacea, Schlumb., with 

 test similar to Euglypha). 



(3) The principal axis of the test undergoes a curvature 

 (thus the snail-shell-like test of Diffiugia spiralis). 



These specialities of outward configuration are valuable 

 specific characters, if not available for the formation of genera 

 or larger groups. The presence or absence of special struc- 

 ture in the test itself and the presence or absence of foreign 



