PULVINULINA. CALCARINA. 141 



likewise peculiar. A larger supply of material might show P. Broeckiana to be 

 only a modification of the species referred to, but the few specimens hitherto found seem 

 very distinct from it. 



Distribution. -In the Calcaire de Namur of Belgium. Very rare. 



Genus. CALCAUINA, D'Orbigny. 



NAUTILUS, Gmelin, Fichtel and Moll. 



ROTALIA, Lamarck, d'Orbigny. Revss. 



SIDEHOLIXA, Defrance, <POrbigny. 



CALCAKIXA, d'Orbigny, Reuss, Carpenter, Parker and Jones, Brady, Giimbel, Schwager. 



ROTALINA, d'Orbigny, Eyyer. 



SlDEEOLITES, SlDEROLITHUS, SlDEROPORUS, SlDEROSPIEA, AsTERIATlTES, OWCtorum. 



General Characters. Test free, convoluted, depressed ; rarely smooth, more 

 frequently tuberculate or rough ; formed of a spire regularly coiled ; convolutions all 

 more or less visible on the superior surface, embracing on the inferior, formed of many 

 chambers. Shell-wall produced at intervals into marginal appendages, often much 

 elongated, simple or furcate, resembling the rowel of a spur. Interior structure 

 remarkable for its tendency to produce supplemental growths of shell-substance forming 

 an intermediate skeleton furnished with a well developed canal-system. Aperture, a 

 longitudinal slit (often bridged over so as to form a line of orifices) in the terminal 

 chamber, close to the penultimate convolution. 



The genus Calcarina is so small and unimportant a constituent of the Carboniferous 

 fauna that there seems no need in this place to enlarge upon its general history. It is 

 much better known as a recent than as a fossil type. The great abundance and large 

 size of the living specimens obtained in tropical seas, together with their striking 

 peculiarities, whether of external form or internal structure, have invested the genus 

 with somewhat unusual zoological interest. 



CALCARINA AMBIGUA, nov. PI. VI, fig. 13. 



One or two small Rotaline shells which there can be little doubt pertain to the genus 

 Calcarina, have been found in the debris of the Belgian Carboniferous Limestones. 

 The exterior of these little fossils is so obscured by age and external agencies, that it 



