104 



BRITISH SILURIAN BRACHIOPODA. 



this Monograph. Those described in the preceding pages are the only British Sihirian 

 species of the genus with which I am at present acquainted. 



In a paper on the Pebble-bed of Budleigh-Salterton, published in the ' Quart. Journ. 

 Geol. Soc., London,' vol. xx, p. 295, pi. xvii, figs. 10 and 13, Mr. Salter describes two 

 species of Spirifera, Sp. antiquissima, Salter, and Sp. Davidsi, Rouault (?), as of perhaps 

 Lower Silurian age ; but that distinguished and experienced palaeontologist does not omit 

 to add, " These are the oldest Isnown species of the genus ; if indeed it be not the case 

 that there are, as above suggested, pebbles from some Devonian rock, mixed with others." 

 Since the above lines were published, I have received from Messrs. Vicary and Valpy the 

 loan of a considerable number of specimens of the above-named species, and I am of 

 opinion that they are of Devonian age, and referable to a single species, that species being 

 Spirifera Verneuilii, Murchison, a well-known and far-spread Devonian shell. I may 

 likewise add, that, after a careful study of several hundred specimens of Brachiopoda 

 from the Budleigh-Salterton Pebble-bed, collected by Messrs. Valpy, Vicary, and 

 Winwood, I was able to make out some thirty distinct species of Brachiopoda, of which 

 more than half are, in my opinion, of Devonian age, while some few only appear to be 

 Silurian. 



Genus — Nucleospira, Hall. 



Hall, Palaeontology of New York, vol. iii, p. 219 (printed in 185", published in 

 1859) ; and Twelfth Report on the State Cabinet, New York, p. 24, 1859. 



rj/peS—NuCLEOSPIRA VENTRICOSA, N. CONCINNA, and N. PISUM. 



Never having had the opportunity of studying the interior character of this genus, 

 otherwise than through the medium of Prof. Hall's description and figures, I cannot do 

 better than reproduce the author's diagnosis. 



"Shell spheroidal or transversely elliptical, more or less gibbous or ventricose, 

 furnished with internal spires as in Spirifer .- hinge-line shorter than the width of the 

 shell ; cardinal extremities rounded : valves subequal, articulating by teeth and sockets. 

 Ventral valve having the beak extended beyond the opposite valve; and beneath it a 

 triangular depression or area, which sometimes terminates in a shallow spoon-shaped pit, 

 on each side of which, at the base, is a strong tooth. A narrow ridge or septum extends 

 along the centre of the inner side of the valve, from beak to base. Dorsal valve furnished 

 with a strong spatulate cardinal process, which, rising vertically from the cardinal margin, 

 is closely grasped at its base by the cardinal teeth of the other valve ; and thence bending 

 abruptly upwards, and expanding, is projected into the cavity of the opposite beak, lying 

 close upon the underside of the false area. This process is grooved or depressed in the 

 centre of the upper side, so as to leave between it and the arch of the ventral beak a 



