56 BRITISH DEVONIAN BRACHIOPODA. 



genus, and has received a great number of different specific denominations. In 1777, 

 several of its varieties were well figured by Schroter, and who, while describing them, 

 did apply to each modification in shape distinctive denominations, such as pectinata, 

 subtilissime striata, cancellata, minutissime striata, &c. The width and number of the 

 striae, as well as of the concentric laminae, constitute the principal differences observable 

 in specimens of this important and curious species. All these modifications can be 

 traced in specimens from any single locality, as is the case at Ferques, in the Boulonnais, 

 France, as well as at Reffrath, near Cologne, in Prussia, where the shell is exceedingly 

 abundant. The beak is usually so closely pressed to the umbone of the dorsal valve, 

 that no foraminal aperture can be perceived ; and this led Dalman, the founder of the 

 genus Atrypa, to suppose that the beak was imperforate. In some examples, however, 

 of A. reticularis the foramen can be perceived : consequently Dalman's term becomes 

 a zoological misnomer, and D'Orbigny's Spiriyerina would be a preferable substitute. 

 The identity of the Silurian and Devonian specimens have likewise been recognised by 

 several distinguished observers. Thus, at page 297 of the second edition of Murchison's 

 ' Siluria,' we find — "Among the Mollusca nearly all the. species of Atrypa, Orthis, and 

 Spiri/er, differ from those of the Silurian era. One shell, however, the Atrypa reticularis, 

 must be mentioned as an exception to the prevalent rule of each great group being 

 distinguished by peculiar forms ; for this hardy species, with which the reader became so 

 familiar in the Silurian rocks, lived on to the Devonian era, and is as common in the 

 limestones and shale of Devonshire as in the older series. It even ranges to the 

 furthest known geographical limits of the Devonian rocks, to Armenia, the Caucasus, 

 and China on the east, and to the Devonian deposits of America on the west!" And 

 again, at page 379 of the work on ' British Palaeozoic Fossils,' Professor M'Coy observes, 

 while treating of Spiriyerina reticularis, that he cannot perceive the slightest difference 

 between some of the Eifel and Upper Silurian and some of our Devonshire specimens. 



Atrypa reticularis occurs abundantly in the Middle Devonian Limestones of Barton, 

 Lummaton, and Hope's Nose, near Torquay. In limestone of a similar age at Dartington 

 and Black Hall, near Totness ; near Plymouth ; at Woolborough and Ogwell, near Newton 

 Abbot; Chircombe Bridge, near West Ogwell ; and Hagginton Hill, near Jlfracombe, &c, 

 in Devonshire. In Cornwall it occurs at Looe ; and, according to Mr. Salter, in the 

 Upper Devonian beds of Petherwin and Landlabe (?). 



On the Continent it abounds at Ferques, Chimay, Couvin, Hay ; in the Eifel ; at 

 Paffrath, Refrath, Lustheide, Hubigenstein (Hartz), Lake Ilmen, Volkof, Voronege, &c. ; 

 also in the Ural, Smeinogorsk (Altai) ; State of Ohio, New York, Tenessee, &c, &c. 



Some modifications (?) of this species may be worthy of varietal denominations. 



