298 PROF. ALLMAN ON THE EECENT EESEAKCHES 



and in the fact, according to GreefF, that they are traversed by 

 minute canals for the transmission of the pseudopodia. There is 

 a large central nucleus with nucleolus. 



Fig. 16. 



Tinacocystis ruhicunda. Jc, endosarc ; r, ectosarc ; 7i, nucleus. 

 (After Hertvvig and Lesser.) 



Acanthocystis and the other skeletophorous Heliozoa whose 

 hard parts are in the condition of detached pieces such as spines, 

 spicula, tablets, and the like, have been united by Hertwig and 

 Lesser into a group to which they give the name of Chalaeo- 

 THOEACA, while those whose skeleton is in tlie form of a connected 

 shell have been combined into a separate group under the name 

 Desmothoeaca. 



Among the Desmothoraca the most interesting is Clathrulina 

 e7e^«««(iig. 17), originally described by Cienkowski,who discovered 

 it near St, Petersburg*. Greeff now gives a very full description 

 of this beautiful little Ehizopod, which he obtained in the neigh- 

 bourhood of Bonn, It had also been found by Haeckel near Jena, 

 while a closely allied, if not identical form had nearly simulta- 

 neously with Oienkowski's discovery been observed by Archer in 

 Ireland and in Wales. 



* Oienkowski, " Die Clathrulina," Archiv f. micr. Anat. 1867. 



