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CARBONIFEROUS AND PERMIAN EORAMINIFERA. 



test, as stout and sandy externally as Lituola ; but not unfrequently the sandy coat is 

 found to be a mere incrustation upon a porous shell, and specimens often occur which are 

 quite porous and smooth externally. So that, although assigned to the Lituolida from its 

 close affinity to the typical Lituoline genera, Valvulina might with almost equal propriety 

 have been placed amongst the Globigerinida, in the sub-order Perforata. The 

 characters of the Carboniferous species strikingly confirm this view of Valvulina as an 

 intermediate group. A large proportion of them are externally smooth : perhaps in the 

 majority of cases they are none the less really arenaceous, but if so, the constituent 

 sand-grains and the cement in which they are embedded are alike calcareous, and the 

 composite structure of the test is less evident than when the sandy particles are siliceous. 

 But in some of the species (notably V. bulloides) the test, though not always smooth, is 

 usually distinctly porous, and a transparent section of the shell does not differ materially 

 from that of corresponding members of the Perforata. 



We are confronted with a new intermediate group in the genus Endotliyra, a type 

 hitherto unstudied, and known only from the section of a specimen figured by Professor 

 Phillips thirty years ago. Somewhat higher in organization than Valvulina, and in 

 its modifications strikingly isomorphic with the Rotaline series, Endotliyra is never 

 conspicuously sandy, never labyrinthic as to its interior structure, and even when the shell 

 is thick and somewhat coarse in texture, it is still smooth externally. Normally the test is 

 opaque and imperforate, but young examples of some species are often so hyaline that the 

 interior arrangement of the chambers may be traced through the outer convolutions, and 

 these thin-shelled specimens may occasionally be porous also. 



To the list of intermediates must be added a number of uniserial forms which here 

 receive collectively the generic name Nodosinella. They are not a little obscure in their 

 structure and affinities, but seem to bear the same sort of relation to the Nodosarine 

 genera that Endotliyra bears to the Rotaline. They are, as has been said, uniserial, 

 thicker-shelled than their hyaline isomorphs, and normally imperforate. What has been 

 said of the structure of the test in Valvulina applies in most respects to the genus 

 Nodosinella as found in the Carboniferous rocks, even to some minute particulars not 

 needful to be entered upon here. In general terms the specimens differ in shell-texture 

 from the moniliform Lituola in much the same degree as the typical Trochammina differs 

 from the rougher Lituoline varieties. 



There is yet one more of these ambiguous groups — that comprising the adherent forms 

 to which I have given the generic name Stac/ieia, a group whose simplest modification 

 consists of a single row of rounded parasitic segments, but which in its more complex 

 development shows some degree of isomorphism with the Rotaline genera Planorbulina, 

 Tinoporus, and Polytrema. The minute structure of the test in Stacheia in its complex 

 forms cannot be satisfactorily decided from the specimens hitherto met with, owing to 

 alterations in microscopic characters produced by the process of fossilization ; but it may 

 be assumed from that of the simpler varieties, which not only present the same sort of 



