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BRITISH DEVONIAN BRACHIOPODA. 



Family— PRODUCTION. 



Genus — Chonetes, Fischer. 



Chonetes Hardrensis, Phillips. PL XIX, figs. 6 — 9 ; and Chonetes (Lept^ena) 



sordida, Soio. PI. XIX, figs. 4, 5. 



Orthis Hardrensis, Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, 



p. 138, pi. lviii, fig. 104, M.*.<U and pi. lx, fig. 104, 1841. 

 Lept^na convoluta, Ibid. Ibid., pi. xxiv, fig. 96. 

 1 — sordida, Sowerby. Trans. Geol. Soc, 2nd ser., vol. v, pi. liii, figs. 5 and 16, 

 1840. 



?Chonetes sarcinulata, Be Kon. Mon. Productus et Chonetes, p. 210, 1847. 



— — Sandberger. Die Brachiopoden Rheinischen des Schysten- 



systems in Nassau, p. 71, pi. xxxiv, fig. 14, 1855. 



— Hardrensis, Davidson. Monog. British Carb. Brach., p. 186, pi. xlvii, 



figs. 12—16, 1861. 



Spec. Char. Shell marginally semicircular, wider than long, concavo-convex ; hinge- 

 line straight, and either a little shorter or somewhat longer than the width of the shell, 

 with rounded or angular terminations; each valve is provided with a sub-parallel area, which 

 is widest, however, in the ventral one, and divided in the middle by a small fissure, partially 

 covered by a pseudo-deltidium ; ventral valve moderately convex, sometimes slightly 

 depressed along the middle and flattened towards its auriculate cardinal extremities j the 

 beak, which is small and incurved, does not overlie the hinge-line, while the dorsal valve 

 assumes in different specimens a greater or lesser degree of concavity, with, at times, a 

 slight longitudinal elevation along the middle, and flatness near the cardinal extremity. 

 The surface of both valves is covered with numerous thread-like, radiating, and often 

 bifurcating striae, which increase in number by the interpolation of striae at various dis- 

 tances from the beak and umbo, so that as many as 120 striae may in some examples be 

 counted round the margin, while at irregular distances small spines rise from their rounded 

 surface in addition to those on each side of the beak ; in adult examples there exist along 

 the cardinal edge from five to nine slanting, tubular spines, which become longer and 

 larger as they approach the extremities of the cardinal edge. Dimensions variable ; an 

 average-sized specimen has measured — 



Length 7, width 11, greatest depth 1^ lines. 



Obs. The above description is taken from that published at page 1S6 of our 

 ' Monograph of British Carboniferous Brachiopoda,' and we must likewise refer the reader 

 to the observations therein appended. The identity of the Carboniferous species with that 



