﻿120 



BRITISH CARBONIFEROUS BRACHIOPODA. 



Lept^ena rlgosa, Dalman. Kongl. Vetensk. Handl. for iir. 1827, pi. cvi, fig. 1. 

 Productus auADRAXGULARis, Steininger. Bemerk. iiber die Verstein. des Eifels, p. 35, 



1831. 



Strophomf.na pileopisis, Dumont. Const. Geol. de la Province de Liege, p. 354, 1832. 



— marsupit. Ibid. 

 Productus elegans, Steininger. Mem. Soc. Geol. de France, vol. i, p. 361, 1834. 

 Strophomena rugosa, lironn. Lethaea, Geog. i, p. 87, pi. ii, fig. 8, 1835. 

 1'roducta analoga, Phillips. Geol. of Yorkshire, vol. ii, p. 215, pi. vii, fig. 10, 1836. 

 Orthis rugosa, V. Buch. Ueber Delthysis, p. 70, 1837. 

 Lept.ena tenuistriata, Sowerby. Sil. Syst., tab. xxii, fig. 2 a, 1838. 



— distorta, J. Sowerby. Min. Conch., vol. vii, p'.. dcxv, fig. 2, 1840. 



— xodulosa, Phillips. Palaeozoic Fossils of Cornwall, pi. xxiv, fig. 95, 1841. 



— depressa, De Koninck. Description des animaux fossiles de la Belgique, 



pi. xii, fig. 3, 1843. 



Leptagonia rugosa, M'Coy. Synopsis of the Characters of the Carb. Foss. of 

 Ireland, p. 118, 1844 (also 1855). 



— multirugata, M'Coy. PI. xviii, fig. 12, 1844. 



Strophomkxa rhomboidalis, var. Analoga, Dav. Carboniferous System in Scot- 

 land. The Geologist, vol. iii, p. 102, 

 pi. i, figs. 26—33, 1860. 



Sp. eh. Shell more or less transversely semicircular or sub-quadrate ; valves geniculated ; 

 hinge line straight, and as long as the greatest width of the shell, with rounded cardinal 

 angles, which are at times prolonged in the shape of expanded wings. The ventral 

 valve is slightlv convex at the beak, from whence it becomes flattened to a certain distance 

 and age, when the valve is suddenly bent downwards at almost right angles.. The frontal 

 margin is undulated, concave near the cardinal angles; it afterwards bulges out laterally, to 

 form in front a slight outward curve. On the flattened portion of the disc, there exists a 

 variable number of slightly undulating and occasionally interrupted concentric wrinkles, 

 which turn outwardlv towards the cardinal angles, and thus follow the marginal curves. 

 The entire surface is also covered with numerous radiating, thread-like striae; and a small 

 circular foramen is generally observable close to the extremity of the beak, and up to a 

 certain age, but which becomes obliterated or cicatrised in the adult. The dorsal valve 

 is concave, and usually follows the curves of the opposite one, and is similarly wrinkled and 

 striated. In the interior of the ventral valve, two diverging teeth articulate with corres- 

 ponding sockets in the opposite valve. The muscular impressions (in this valve) are 

 margined by a semicircular ridge, continued from the base of the teeth, and curving on 

 either side so as to produce a saucer-shaped depression j the adductor or occlusor leaves a 

 scar on either side close to a small median ridge, the cardinal or divaricator muscle filling 

 on either side the anterior portion of the cavity ; the ventral adjustor and pedicle 

 muscles do not appear to have produced any very definite impressions, but it is highly 

 probable that an attachment for these muscles existed in the posterior portion of the 

 saucer-shaped depression above described, from the fact that a small circular peduncular 

 foramen is also observable at a small distance from the extremity of the beak, and which 



