384? Mr. Weaver's View o/* Eh ren berg's Observations 



Flustra^ luhulipora^ and similar forms. The simplest Poly- 

 thalamian form is the Miliola in Dujardin's sense, if there be 

 really such self-existent animals, and they be not the young 

 of others, or of many- celled forms most nearly related to Bi- 

 loculina. And perhaps Gromia oviformis might be so viewed, 

 should it not prove lo be a Dijffiugia (an Infusoria). In this 

 series I myself place provisionally, as doubtful, those nume- 

 rous small globules of the sand of Rimini which have no di- 

 stinct opening, or sometimes present a very minute one. The 

 next simplest form is that of a simple straight row of cells, as 

 in the Nodosaria, a jointed continued development of a sim- 

 ple body. Tea,'tularina, Uvellina and Eotalina (Lenticulina), 

 ma}^, as to external form, be viewed as Nodosarina developed 

 in another manner, namely, in botryoidal or spiral forms. 



I have here to make a remark that appears important. In 

 the entire vast mass of known Polythalamia, a case or vest- 

 ment prevails which is either cuticular or composed of a cal- 

 careous substance, while in Infusoria either a cuticular or sili- 

 ceous substance prevails, so that hitherto no calcareous-shelled 

 Infusoria nor siliceous-shelled Polythalamia had presented 

 themselves. Yet among the fossil microscopic organisms of 

 the chalk marl of Sicily, we find intermingled with the Infu- 

 soria shells bodies whose forms may be ranked with Poly- 

 thalamia, namely, with Nodosarina, but the shells of which 

 are siliceous, insoluble in acids, and which to the eye have a 

 more transparent vitreous aspect than the calcareous shells 

 when penetrated by balsam. I have hence been induced to 

 place these siliceous-shelled forms, until a further knowledge 

 may be acquired of their organization, among the polygastric 

 Infusoria near the shelled Amoeba, in a separate family, under 

 the name o{ Arcellina composita, or Polycystina^ . Such sili- 

 ceous-shelled Polycystina^ resembling calcareous-shelled Po- 

 lythalamia, are the genera Lithocampe^ CormiteUa and Ha^ 

 liomma, with several species. 



I wish here to draw attention to a small character hitherto 

 unregarded, which is distinctive of true Polythalamia, and 

 often even of their fragments. It consists in this, that in the 

 tube or channel of connexion between the cells, the mouth of 

 the tube which belongs to the earlier smaller cell is overgrown 

 and surrounded by the succeeding larger cell. If the mouth 

 of the last cell be prolonged in a beak-like form, we find in 

 all the earlier smaller cells a distinct tube, quite similar to the 

 hard remains of the sipho in the Nautilus; but so placed that 

 the tube always projects forward from the smaller into the 

 larger cell, and never backward from the larger into the smaller 



* This view has been already indicated in the work "On the Infusoria 

 as perfect organisms," 1838, p. 136. 



