418 Prof. M. Schultze on Polytrema miniaceum. 



Carpenteria otherwise than in Polytrema. The calcareous shell 

 in both cases is completely Foraminiferoid. The siliceous spi- 

 cules lie scattered in the chambers, and are enveloped by but a 

 small residue of organic substance. The central chambers (and 

 this is of particular importance) were filled, in Carpenteria, also 

 with a firmer yellowish-brown substance containing no spicules, 

 exactly as in Polytrema. Lastly, the form of the spicules, ac- 

 cording to Carpenter's figures (/. c. pi. 22. fig. 16), agrees almost 

 exactly with that of those found in Polytrema, inasmuch as 

 they are either pointed at both ends or knobbed at one end, 

 bowed, and of small size. 



As might have been expected, it occurred to Carpenter also 

 that the spicules might be referred to a Sponge living pa- 

 rasitically in the Polythalamian. But, in finally coming to 

 the conclusion that both belong to one organism, he lays 

 particular stress upon the discovery of the above-mentioned 

 yellowish-brown organic substance in the cavities of the central 

 chambers, regarding this as true sponge-substance, without 

 spicules indeed, but too dense and firm to be taken for the 

 sarcode-body of a Polythalamian. Here Carpenter is in error. 

 As I have already stated, from innumerable examinations of 

 Polythalamia and Sponges, both dry and preserved in spirits, 

 the substance of the Polythalamia is much denser, firmer, and 

 more resistant than the organic substance of the Sponges. With 

 the exception, of course, of the horny substance of the horny 

 Sponges, the organic envelope of the sponge-spicules breaks up 

 and becomes decomposed with such remarkable ease and rapidity 

 that I have never succeeded with spirit-specimens of Sponges, 

 even when I had myself put them quite fresh into spirit, in iso- 

 lating moderately large coherent portions of the organic sub- 

 stance, or making any investigations into its nature. In Poly- 

 thalamia, on the contrary, in which the organic substance is so 

 resistant that it remains capable of life for weeks even in the 

 midst of decaying substances, and that they may be kept alive 

 for months far more easily than any other marine animals, the 

 action of spirit or desiccation causes such a hardening that the 

 contents of the chambers may be isolated precisely in the state 

 which Carpenter adduces in opposition to their Polythalamian 

 nature. 



For this reason I cannot regard the conditions in Carpenteria 

 otherwise than as in Polytrema, and therefore believe that the 

 boundary between Polythalamia and Sponges, which has hitherto 

 been considered as a very sharp line, must still be maintained in 

 all its integrity. 



