SPIRIFERA. 41 



Spirifera Urii, Fleming, 1828. PI. IV, figs. 25—28. 



Spirifek Urii, Fleming. British Animals, p. 376, 1828. 



Atrypa unguiculus, J. Sow. Trans. Geol. Soc, 2nd ser., vol. v, pi. Hv, fig. 8. 



Spirifera — Phillips. Pal. Foss. of Cornwall, Devon, and West Somerset, p. 69, 



pi. xxviii, fig. 119, 1841. 



Spirifer — A. Roemer. Dei Versteinerungen des Harzgebirges, pi. iv, fig. 22. 



Martinia Clannyana, King. Cat. of the Organic Remains of the Permian Rocks of 

 Northumberland and Durham, 1848; and Mon. of English Per- 

 mian Fossils, p. 134, pi. x, figs. 11 — 13, 1850. 



Spirifera Urii, Bav. Mon. Carb. Brach., p. 58, pi. xii, figs. 13, 14 ; and p. 267, pi. liv 

 figs. 14, 15. 



Spec. Char. Shell small, suborbicular, rather wider than long ; hinge-line shorter 

 than the greatest breadth of the shell ; cardinal angles rounded. Dorsal valve semicircular, 

 slightly indented in front, with a narrow hinge-area ; nearly flat or but slightly convex — 

 most so at the umbone — with a shallow mesial furrow, commencing at a short distance 

 from the umbone and extending to the front. Ventral valve much more convex and deep 

 than the opposite one, with a comparatively large, incurved beak, and longitudinal farrow, 

 commencing at the extremity of the beak and extending to the front. The area is 

 triangular and of moderate length and width, the fissure being partly arched over by a 

 pseudo-deltidium. The external surface, where perfect, is covered with small spinules. 

 Dimensions variable. 



Length about 4, width 4^, depth 2 lines. 



Obs. This little species has been fully described in the second volume of this work ; 

 therefore all we need now repeat is, that the Permian, Carboniferous, and Upper Devonian 

 specimens are identical in shape and character, as a comparison of specimens, as well as of 

 the figures, will sufficiently prove. This identity has been likewise recognized by Professor 

 Morris, at p. 154 of his 'Catalogue,' by Messrs. Salter, llowse, Kirkby, De Verneuil, and 

 myself, and by Sir R. Murchison, who does not omit to mention, at p. 299 of the second 

 edition of his admirable ' Siluria,' that Spirifera Urii, Sp. disjuncta, and Orthis interlineata, 

 are found associated together, and that they are common fossils of the Barnstaple or 

 Marwood and Pilton series, as well as in that of South Petherwin ; these beds being 

 referred by the above-named and celebrated geologist to the Upper Devonian of this 

 country. 1 



1 This is not the place to discuss the much controverted question relating to the real or supposed value 

 or claims of the Devonian formation, that is to say, whether it should or not be considered a distinct and 

 independent system ; but, as I have often to make use of the provisional terms " Upper" and "Middle 

 Devonian" with reference to the fossils described in this monograph, a few lines of explanation may now 

 appear to be absolutely required. 



Some geologists have gone so far as to suggest that the so-termed Devonian, as a system, could be ad- 



F 



