184 BRITISH CARBONIFEROUS BRACHIOPODA. 



narrow ; surface of both valves covered with numerous fine, radiating striae, which become 

 more numerous as they proceed from the beak and umbo to the margin from bifurcation 

 and interstriation. Spines few on the surface of the ventral valve, but a row of longer 

 ones rise from and follow close to the cardinal edge. Interior unknown. Dimensions 

 variable ; a British example measured — length 8, breadth 14 lines. 



Obs. I am but very imperfectly acquainted with this species. Certain fragmentary 

 specimens from the lower Scar limestone of Settle, in Yorkshire, could not be distin- 

 guished from some small Belgian examples of C. Ddlmaniana I had received from 

 Prof, cle Koninck, and for which reason the species (?) is, with some uncertainty, here 

 provisionally introduced. The specimens I have been able to examine of the shell under 

 description appear to me intermediate in shape and character between C. papilionacea 

 and C. Hardrensis. Prof, de Koninck mentions that it can be distinguished from the 

 young age of C. papilionacea by its greater curvity (or convexity) and longer cardinal 

 spines ; it appears, also, to attain larger dimensions than C. Hardrensis, which some 

 examples very closely resemble. Prof, de Koninck has given as synonyms of his 

 species Leptcena {Chonetes) volva and L. {Chonetes) mnltidentata of M'Coy, but I 

 cannot coincide with this determination, for, as already stated, C. multidentata, M'Coy, 

 evidently belongs to C. papilionacea, and I am almost disposed to look upon C. volva as a 

 variety of C. Hardrensis? 



Chonetes Buchiana, Be Koninck. PI. XLVII, figs. 1 — 7, and 28. 



Chonetes Buchiana, Be Kon. Descrip. des Anim. foss. du Terr. Carb. tie Belgique, 

 pl.xiii, fig. 1, 1843. 

 — — Dav. A Monograph of Scottish Carb. Brachiopoda, pi. ii, 



fig. 1, 1861. 

 Leptcena crassistria, M'Coy. Synopsis of the Carb. Foss. of Ireland, tab. xx, 



fig. 10, 1844 ; and British Carb. Foss., pl.iiin, fig. 5, 185j. 



Spec. Char. Shell marginally transversely semicircular, concavo-convex, about one 

 third wider than long; hinge-line straight, and either a little shorter, with its cardinal 

 angles rounded, or exceeding the width of the shell, with rectangular or slightly acute and 

 extended terminations. Both valves are provided with narrow sub-parallel areas ; the 

 ventral one, which is the largest, being divided by a small fissure, partially covered with a 

 pseudo-dcltidium, while in the middle of the ventral one there exists a prominent, V-shaped 

 cardinal process. The ventral valve is moderately convex, and flattened towards its auri- 

 culate cardinal extremities. The beak, which is small and incurved, does not overlie the 

 hinge-line. Dorsal valve concave, following the curves of the opposite one. Exteriorly 

 the surface of the ventral valve is ornamented with from twelve to thirty generally simple 

 ribs, with wider or narrower interspaces, the lateral ribs being sometimes larger than those 

 which occupy the middle of the shell ; the dorsal valve is similarly ornamented. Spines 



