BY DR. R. VON LENDENFELD. 149 



6. Hexactinellidse. 0. Schmidt with hexaradiate spicules. 



7. Calcispongise. de Blainville, calcareous skeleton. 

 Selenka (145) described a most interesting form of a sponge, 



which is radially symmetrical ; it has eight radii. He studied the 

 development of this sponge, which is the first in which a structure 

 of this kind, corresponding so closely to the Corals, has been 

 observed. (146.) 



The Histology of the sponges was particularly investigated by 

 Schulze (1. a), who published his results in a series of papers 

 between 1875 and 1880. These works, models of accuracy, 

 have proved that the sponges are not Protozoa, with such evidence, 

 that even the staunchest holders of that theory have not tried to 

 oppose this evidence. The conclusive results contained in these 

 essays appear under the heading " Histology." 



Keller (147) wishes the sponges to be separated from other 

 Metazoa, but he is far from considering them as Protozoa or 

 colonies of such any more than other animals. 



0. Schmidt (148) dwells on the individuality of the sponges, on 

 which cpiestion their systematic position of course greatly depends- 

 The views on this subject are the following : — 



Carter (149) considers the single cell (Spongozoan) as the indivi- 

 duality, whilst Merejkovsky (150) states that the ciliated chambers 

 should be considered as the individuals. Haeckel (151) and with 

 him most authors were of opinion, that the individuality in the 

 sponges is expressed by the Osculum ; any sponge consists of as 



(145). E. Selenka. Uber einen Kieselschwamm von ashtstrahligem Bau. 

 Z. f. w. Z. Band, XXXIII., Seite, 467. 



(146). F. E. Schultze described a similar radial structure in other Sponges 

 at the " Versammlung deutscher Naturforscher und Aerzte" in Eisenach, 

 1882. 



(147). C. Keller. On the systematic position of Sponges. Ann. Mag. (5). 

 Vol. V., p. 268. 



(14S). Schmidt Die Spongien des Meerbusens von Mexico. Jena., 1880. 



(149J. H. Carter. On the nature oj the seed-like body of Spongilla. Ann. 

 Mag. Vol. XIV., p. 97. , , 



(150). C. Merejkovsky. Etudes sur les Eponges de la mer blanche. Mem. 

 Acad. Imp., Petersbourgh. Tom. XVI., p. 13. 



(151). E. Haeckel. Die Kalkschwamme. Berlin, 1872. 



