Prof. M. Schultze on Polytrema miniaceum. 423 



able progress during tbe last ten years, is strikingly shown by 

 the fact that the most experienced student of the Foraminifera 

 in Germany, Professor Reuss, of Prague, in his most recent 

 works, proposes a systematic distribution of these animals ac- 

 cording to exactly the same principles as those adopted by Car- 

 penter. Reuss's chief work, "Entwurf einer systematischen 

 Zusammenstellung der Poraminifereu," is printed in the Number 

 of the * Proceedings of the Academy of Sciences at Vienna ' for 

 October 1861, and is cited by Carpenter in the bibliographical 

 section of his last work (p. xxi. no. xci. a), but appears to have 

 reached him after the impression of the text, as it is nowhere 

 quoted in the latter. In it (see especially the ' Nachschrift,' 

 p. 394) the Foraminifera are divided, as by Carpenter, into those 

 with non-porous and those with porous shells; and, as Reuss 

 excludes the Gromida, there remain two groups in the first 

 section, — (1) those with sandy siliceous shells; (2) those with 

 compact porcellanous shells. In the second group Reuss dis- 

 tinguishes — (1) those with finely porous, hyaline calcareous 

 shells ; (2) those with manifoldly (?) porous calcareous shells ; 

 (3) those with calcareous shells permeated by ramified systems 

 of canals. It is evident that the systems of Carpenter and 

 Reuss perfectly agree. In its further development, however, I 

 am inclined to prefer that of Reuss, as he distinguishes smaller 

 families, more closely following the necessities of the zoologist 

 and the previous systematic works, and, I believe, agreeing 

 better with nature. 



EXPLANATION OF PLATE VIL 



Fig. 1 . A specimen of Polytrema miniaceum from the surface of a Crab ; 



magnified 15 diameters. 

 Fig. 2. Part of the surface of the same Polytrema ; magnified 300 dia- 

 meters, to show the apertures of the pore canals. 

 Fig. 3. Thin section through the calcareous wall of Polytrema ; magnified 



300 diameters. 

 Fig. 4. Part of the animal-body of a Polytrema preserved in spirits, laid 



bare by muriatic acid. In the place of the thick calcareous wall, 



only the membranous linings of the pore canals are retained in 



situ. 

 Figs. 6, 6 & 7. Parts of the body similarly prepared. Fig. 6 shows the 



spiral arrangement of the chambers, probably the first-formed 



part of the Polytrema. 

 Fig. 8. Membranous lining of the chambers without the body, or with only 



a few traces of the latter j isolated by acid. 

 Fig. 9, Two membranous linings of pore canals, with many indications of 



joints. 

 Fig. 10. Siliceous spicules from different chambers of Polytrema. 



