226 Mr. H. B. Brady on a 



September last I described a minute fossil, Archcedtscus 

 Karreri, the chief interest of which lay in two facts : — first, 

 that whilst strikingly Nummuline in its essential features, it 

 presented a wide divergence in some not unimportant points 

 of structure from the typical Nuramulite ; and, secondly, that 

 a fossil with such generic affinities occurred low down in the 

 Carboniferous series at localities far a])art. The descrijJtion 

 of Archiediscus had scarcely appealed * when I received from 

 my friend M. Ernest Vanden Broeck, of Brussels, a couple of 

 packets of calcareous material, which had been foi^warded with 

 the idea that it might be of service to me in investigating the 

 Foraminifera of the Carboniferous period. 



The total number of Foramuufera which accrued from a 

 patient search through the contents of the two packets was 

 exceedingly small. Not more, perhaps, tlian three species 

 were represented. One of them is a familiar Carboniferous 

 form ; and another, of which only a single specimen was found, 

 may turn out to be ncAv. Neither of these need be noticed at 

 present, as my object is with tlie third, which even cursory 

 examination showed to be a true and most characteristic little 

 Nummulite. Happily in the present instance no doubt need 

 exist as to geological origin ; for both locality and horizon are 

 very accurately stated by M. Vanden Broeck ; and though I 

 hope at a future time, when I may have a larger supply of spe- 

 cimens to work upon, to be able to elucidate further some minor 

 details of structure, tlie material at hand has been sufficient to 

 serve for the demonstration of all essential characters. 



Zoologiccd Characters and Structure. — Externally these 

 little fossils are convex disks ; the larger specimens are about 

 •3V inch in diameter and yV inch thick ; the periphery is usually 

 blunt and rounded rather than acute. They are bilaterally 

 symmetrical or nearly so, white and smooth as to surface, 

 the uniformity being broken only by radial lines more tians- 

 parent in texture than the rest of the shell. A section on the 

 median plane reveals a spiral of three or four convolutions, the 

 whorls being nearly ecpial in width or only increasing slightly 

 toAvards the periphery, a primordial chamber relatively rather 

 large, the ordinary chambers few in number for a Nummulite, 

 and bounded by curved septa. 



The characters thus broadly stated may now be examined 

 in detail. 



With respect to the exterior but little more need be said. 



The relation between the diameter and thickness is apparently 



tolerably constant — that is, about as 2j to 1 ; larger examples, 



however, exhibit some tendency to spread out and grow thinner 



* Vide Ann. & Mag. Nat. Hist. October 1873, p. 286. 



