Prof. M. Schultze on Polytrema rniniaceum. 419 



Supplementary. 



In combination with W. K. Parker and T. Rupert Jones, two 

 naturalists who have made themselves celebrated by their re- 

 searches upon Foraminifera, Dr. Carpenter has just published a 

 great work, through the medium of the Ray Society, under the 

 title of ' Introduction to the Study of the Foraminifera.' In this 

 (pp. 235 ei seq.), Polytrema, which was only mentioned inci- 

 dentally by Carpenter in his previous works, is described in 

 detail, and illustrated by figures (pi. 13. figs. 18-20). Dui'ing 

 a visit which I lately paid him in London, Dr. Carpenter had 

 the kindness to show me his rich collection, including his pre- 

 parations of Puhjtj'ema. Although his specimens were obtained 

 from the South Sea, and mine from the Mediterranean, and 

 his exhibit more variation than mine in their external form, I 

 do not think tliat there can be any doubt as to their specific 

 identity. Carpenter has arrived at the same result as myself — 

 namely, that Polytrema is a Polythalamian. His investigations 

 have, however, been made only with dried specimens, and have 

 no reference to the organic contents of the chambers. Carpenter 

 had no inducement to discuss the question whether Polytrema 

 produces spicules, and is thus allied to Carpenteria, as his spe- 

 cimens contained no spicules in their interior. Nevertheless he 

 mentions having seen specimens with the surface entirely covered 

 with a parasitic Sponge, the spicules of which, however, pene- 

 trated scarcely, if at all, into the interior of the chambers. By 

 this means Carpenter establishes a sharp distinction between 

 Polytrema and Carpenteria. If in the former there could be no 

 doubt as to the parasitic nature of the Sponge, as to the second 

 Carpenter still adheres to Gray's opinion that the sponge-spicules 

 are produced in the interior, and that Carpenteria is consequently 

 a transition-form between Sponges and Foraminifera. Perhaps 

 my observations upon Polytrema, which indicate the remarkably 

 close affinity between that genus and Carpenteria, may serve to 

 shake Carpenter's faith in his opinion. 



Upon the systematic position of Polytrema among the Poly- 

 thalamia I have hitherto said nothing, except mentioning its 

 near affinity in appearance with my genus Acervulina. The 

 Acervulinidce, which form a peculiar family in my System of the 

 Polythalamia as established in 1854, are characterized chiefly by 

 the irregularity of their growth, in consequence of which they 

 appear like a misshapen aggregation of chambers deposited one 

 upon the other without any- definite system. I was indeed aware 

 that in several families, especially that of the Rotalidce, an irre- 

 larly growing form may be produced from a Polythalamian 

 which was at first regularly spiral ; but these, from their com- 



