60 BRITISH CARBONIFEROUS BRACHIOPODA. 



Spirifeba decora ? Ibid., fig. 9. 



Spirifeb l^evigatus, F. Buck. Memoirs de la Soc. Geol. de France, vol. iv, p. 198, pi. x, 

 fig. 25, 1840. 



— GLABER, De Eoninck. Animaux fossiles de la Belgique, p. 267, pi. xviii, fig. 1. 

 Mabtinia glabra, M'Coy. Synopsis of Carb. Foss. of Ireland, p. 139, 1844. 



— OBTUSUS and oblatus, M'Coy. Ibid. 



Spirifeba glabra, M'Coy. British Palseozoic Fossils, p. 428, 1855. 



Spec. Char. Very variable in shape and proportions ; transversely oval, rarely as long 

 or longer than wide. Valves almost equally convex, with a mesial elevation or fold in the 

 dorsal, and a sinus in the ventral valve. Hinge line much shorter than the greatest width 

 of the shell ; cardinal angles rounded ; beaks rather approximate, that of the larger or 

 ventral valve prominent, incurved, and of moderate dimensions. A hinge area in the 

 dorsal valve, that of the ventral one triangular and of moderate dimensions, with its 

 lateral margins more or less sharply defined ; fissure partially covered by a pseudo- 

 deltidium. The mesial fold in the dorsal valve is either slightly and evenly convex, rising 

 gradually from the lateral portions of the valve, or abruptly elevated, with a longitudinal 

 depression along its middle, which is also at times reproduced in the sinus of the ventral 

 one. The spiral appendages are large, and occupy the greater portion of the interior of 

 the shell.^ Surface of valves in general smooth, but sometimes a few obscure rounded 

 ribs may be observed on their lateral portions. Dimensions taken from five examples 

 have produced — 



Length 32, width 43, depth 26 fines. 



,, ol, ,, oo, ,, 21 „ 



„ 24, „ 34, „ 13 „ 



j> '-'4, ,, 25, ,, ly „ 



„ 14, „ 13, „ 8 „ 

 Ohs. Martin's illustration of Sp. (glabra is one of the many modifications assumed by 

 this very variable species, and I feel disposed to agree with Professor De Koninck, while 

 considering Sj). oblatus and 8. obtusus (Sow.), Sp. symmetrica, Sp. lingmfera, and Sp. de- 

 cora, of Phillips, as simple varieties or variations in shape of Martin's shell. In the 

 ' Synopsis of Carboniferous Fossils,' Professor M'Coy retained afi the above-named shells 

 as distinct species, but in his more recent work on ' British Palaeozoic Fossils,' Sowerby's 

 two shells are reduced to the rank of varieties of glabra, and there can exist no 



• I have already had occasion to remark, at p. 81 of my General Introduction, that in p. 139 of his 

 'Synopsis,' Professor M'Coy has descril)ed and represented the spiral appendages oi Spirifera {Martinia) 

 glabra so small as only to occupy the rostral half of the shell, but this has been proved incorrect, for all 

 the specimens obtained in \?hich the spirals were preserved, have shown them to be as large as iu any 

 other species of the genus. Fig. 9 of my Plate XI is a representation drawn from the original example 

 figured by Sowerby in tab. 268 of the ' Min. Con.,' thirteen years prior to the publication of M'Coy's 

 'Synopsis.' 



