BRITISH SILURIAN BRACHIOPODA. 121 



Athtris subquadrata, Hall. Report on the Geol. Survey of the State of Iowa, p. 703, 



pi. xxvii, 1858. Carboniferous; Chester, Illinois. 



This species has been worked out by the Rev. N. Glass, and found to be possessed 

 of a true Athyris loop. 



Mr. Glass has also developed the interior of another species, nearly related to A. 

 Jtoysii, from the same formation and from Ellettville, Illinois, and found it also to be 

 possessed of a true Athyris loop. The surface of the shell is covered with concentric 

 lines and closely-packed spiny projections. 



Genus — Nucleospira, Hall, 1859. 



NucLEOSPiRA coNciNNA, Hall. Gcol. 4th District New York ; Devonian. Hamilton 



group, Hamburg, near Buffalo; also from Ontario, 

 Canada. 



This species has been developed by the Rev. N. Glass, who found its spirals, loop, 

 and attachments to be like those of N. pisum. Externally it has the same shape as the 

 Silurian species, and the surface of its valves is also covered with spines. 



Genus — Atrypa, Dalman, 1828. 



Atrypa LARA, Billings, sp. = Athyris lara, Billings. Catalogue of the Silurian Fossils 



of Anticosti; Geol. Survey of 

 Canada, p. 47, 1866. 



This small species is lenticular in shape and obscurely subpentagonal ; both valves 

 moderately convex ; beak small and closely incurved ; surface smooth. Length 3 lines, 

 by about the same in breadth. 



Dr. Hinde having sent Mr, Glass several specimens of this interesting little shell he 

 was able to expose its spirals in a very beautiful manner, and these entirely resemble 

 those of Atrypa, the apex of each vertical cone being directed towards the middle of the 



