310 Mr. Weaver's View o/'Ehrenberg's Observations 



the discs are twice as thick as in Sorites. If we compare So- 

 rites with Flustra^ we may place Amphisonis by the side of 

 Eschara, but, being both free moving bodies, they are different 

 from them. 



Plate IV. contains the invisible a?iimalcules of the chalk 

 and chalk marl, displayed in twelve specimens of rock ; 1 to 9 

 being portions from the chalk, and 10 to 12 from the chalk 

 marl, magnified 300 times. In these specimens the calcare- 

 ous Polythalamia amount to sixteen species, and the siliceous 

 Infusoria to twelve species, with siliceous spicula of sponges. 

 The twelve localities from which these specimens of the rock 

 masses were derived are the following: — ^No. 1 to 5, writing 

 chalk', namely, 1. from Puszkary, in Poland, opposite Grod- 

 no, from the shore of the Memel; 2. from Jiitland, in Den- 

 mark; 3. from the island of Riigen in Pomerania; 4. from 

 Gravesend, on the Thames; 5. from Meudon, near Paris; 

 ^firmer writing chalk. No. 6, from Cattolica in Sicily; com^ 

 pact, not writing chalk, No. 7, from the Mokattuni hills near 

 Cairo; and No. 8, from the Catacombs of Thebes in Upper 

 Egypt; compact gray limestone. No. 9, from the mountain 

 mass of Hamam Faraun in Sinai, Arabia; chalk marl. No. 

 10, from Gran in Africa; No. 11, from Caltasinetta in Sicily; 

 No. 12, from Greece. 



In \\\^ general table indicated above, under the head of No. 

 13 of the contents of the memoir, a list is given of the princi- 

 pal forms of the invisible organic bodies which constitute 

 the rocks from which the twelve above-mentioned specimens 

 were taken, as well as the chalk of Brighton, the chalk marl 

 of Zanle in the Ionian Islands, and the nummulite limestone 

 of the Pyramids of Geza in Egypt. From this it results that 

 the principal forms in these rocks consist of twenty-five spe- 

 cies of calcareous-shelled Polythalamia, thirty-nine species of 

 siliceous-shelled Infusoria, seven species of soft-shelled Infu- 

 soria of the flints, and five species of siliceous plants. 



The twenty- five species of calcareous-shelled Polythalamia, 

 belonging to eight genera, are the following: — 



Flustrella concentrica\ Globigerina bulloidesl, G. helicinal\ 

 Planulina sicula, P. '^turgida-, l^ohuWuo. cretacea; Rosalina 

 yhveolata, ^. globular i si, ^. Hcevigata, 'R.pertusa; Rotalia 

 ^globulosa, R. ocellata, R. ornata, R. perforata, R. scabra, 

 R. stigma ; Textularia acicidata ?, T. '*aspera, T. brevis, T. 

 ^dilatata, T. -^globulosa, T. perforata, T. spinosa, T. * striata ; 

 Turbinulina italica'l Quinqueloculina? from Benisuef, is 

 doubtful. N.B. Textularia globidosa, when in fragments, is 

 not easily distinguished from Rotalia globulosa ; and in like 

 manner the fragments of Textidaria perforata may be con- 

 founded with Rotalia perforata. 



