ATHYRIS. 13 



St rig. dorsalis, D'Archiac and De Verneuil, is a variety having a more or less distinct 

 median groove upon each valve, this groove being prolonged to the beak of the ventral 

 valve and only to about the middle of the dorsal one. It is, however, a mistake to suppose 

 that it is only this variety which has its surface covered with delicate, longitudinal strise, 

 for I have observed the same on some well-preserved German specimens which had no 

 groove in either valve. 



Strivgocephalus Burtini has assumed many shapes and degrees in the projection and 

 incurvature of its beak, and Professors De Koninck and Suess, who have along with 

 myself examined the original example of M'Coy's Uncites lavis (PI. II, fig. 9, of this 

 monograph), have expressed it to be their opinion that the last-named shell is nothing 

 more than an exceptional, much elongated example of Defrance's String. Burtini. 



Striugocephalus Burtini is a characteristic fossil of the Middle Devonian limestone or 

 " Stringocephalen-Kalk " of the Germans. In England it occurs in South Devonshire 

 at Plymouth ; Bradley, near Newton ; and Chircombc Bridge, near Ogwell. In North 

 Devon at Combe Martin and Hagginton. Mr. Valpy states that he found a specimen 

 in the limestone of Ilfracombe. 



On the Continent it is very abundant at Paffrath, near Cologne, at Villmar, and in the 

 Eifel ; also at Diete, Brilon-upon-the-Lahr, and at Chimay and Nimes in Belgium, &c. 



Family— SPIRIEERID^E. 



Genus — Atiiyris, M' Cog; 1 vel SrntiGERA, D'Orh. 



1 In 1853, while publishing my 'General Introduction' in the first volume of the present work, I 

 proposed to apply the term Athyris, M'Coy, to shells such as Atrypa iumida, Dal., and Terebratula 

 Herculea, Bar., and to make use of D'Orbigny's better name Spirigera for those species with a perforated 

 beak, such as Athyris concentrica. This view or substitution of names and shells was subsequently objected 

 to, it being justly considered that as M'Coy's generic designation of Atbyris was intended for shells such 

 as A. concentrica, that it could not be correctly applied to another group of species. Therefore, much to 

 my regret, but in order to adhere to the law of priority, I subsequently restored to Athyris A. concentrica 

 and its congeners, and made use of Merista for those to which I had, in 1853, applied the term Athyris. 

 I believe, however, that with time the term Athyris will be completely disused, and that of Spirigera 

 preferred, as the law of priority should not be allowed to perpetuate a palpable zoological misnomer. Mr. 

 R. Jones is of opinion that generic, being group names, may be improved upon (see his ' Monograph on 

 Estherise,' p. 11, note). 



In the 'Thirteenth Annual Report of the Regents on the State Cabinet of New York,' published in 

 1860, Professor Hall makes some interesting observations on the subject, which we will transcribe, as 

 being little known in this country. 



" Among the fossils referred for many years to Terebratula, Atrypa, &c, European authors have 

 separated the genera Athyris and Merista, shells which have many characters in common, and which 

 were, indeed, at first united under Spirigera or Athyris, until in 1851 the genus Merista was proposed by 

 Professor Suess. In my later studies of the Brachiopoda of the American Palaeozoic strata, I have referred 

 to the genus Athyris certain species which have a subglobose or ovoid form, with lamellose surfaces, and 



