290 W. ARCHER. 



genera ; nay, cases are not wanting where different observers 

 would seem each to have named, as a new genus and species, 

 one and the same thing. Such cases I would try to point 

 out in the course of the resume. 



On the whole it appears preferable to commence our 

 review of newly described forms with the Heliozoa, to pass 

 thence to the Monothalamia and conclude with Hertwig and 

 Lessor's new forms not belonging to either and grouped 

 together simply as a " mixed lot." Necessarily it would be 

 impossible to give the whole of the matter in full, as it would 

 suffice to fill several numbers of this journal, and we must 

 be content with an effort at an epitome and by reproduction 

 of certain typical figures to afford home microscopists an 

 opportunity to identify, at least approximately, such of these 

 forms as they may encounter. 



After giving a short historical resume of the views of 

 previous Avriters^ on those ** Rhizopods " referred to by them 

 as " Freshwater Radiolaria," and who, on the whole, Avere 

 inclined so to designate them, Hertwig and Lesser, approach- 

 ing the consideration of the question with what right these 

 debateable organisms can be regarded as appertaining truly 

 to the " Radiolaria," propound first the query, " "What are 

 the conditions of organization characteristic of the Radio- 

 laria?" for, as they rightly hold, upon the answer thereto 

 would depend the reply to the further question, " How far 

 these characteristic conditions of organization can be de- 

 monstrated in the * Freshwater Radiolaria.' " 



In accordance with Hackel's views as to the true 

 (marine) Radiolaria, the following are the characteristics of 

 that class : 



1. They are multicellular organisms, nucleated, and con- 

 taining imbedded in their protoplasm numerous perfectly 

 independent walled cells. 



2. They all possess a " central capsule," that is, a multi- 

 cellular structure, posed in the centre of the body, mostly 

 of globular figure and surrounded by a thick chitinous mem- 

 brane. 



3. Most of them possess yellow-coloured cells (for the 

 most part imbedded in the outer sarcode), the so-called 

 " yellow cells." 



^ Focke, 'Zeitscrift fur wiss. Zool./ Bd. xviii, p. 345 ; Cienkowski, 

 'Archivf. Mikr. Anat.,' bd. iii, p. 311 ; Carter, 'Ann. and Mag. Nat. 

 Hist.,' 3. Ser., vols, xii and xiii; Grenacher, ' Zeitschrift f. wiss. Zool.,' Bd. 

 xix, p. 289 ; Greeff, 'Archivf. Mikr. Anat.,' p. 464; Archer, ' Quart. Journ. 

 Micr. Sci.,' vol. ix, pp. 250, 386 ; x, pp. 17, 101 ; xi, p. 107. 



