266 TWilNTIETH REPORT ON THE STATE CABINET. 



a recent publicatioE§ of Prof. M'Coy, that he has added to the diagnosis of Athyris 

 a trifling but important ijaodification, which is, ' that there exists a strong median 

 septum in the rostral portion of the entering value; the dental lamellce are moderate; 

 there is no foramen. Example A. tumida, Dalm.' This diagnosis in no way befits the T. 

 concentrica; but on the contrary, it accords perfectly with the condition observable in 

 the group characterized by the T. tumida and herculea. It is evident, from all this, 

 that nearly all authors have united two distinct groups of shells under the name of 

 Athyris or that of Spirigera. In order to put an end to this confusion, and to avoid 

 at the same time the necessity of new names, I proposed, in the English edition of 

 my British Fossil Brachiopoda, 1853, to preserve the name Athyris for the group 

 characterized by the T. tumida, herculea, scalprum, etc., and the name Spirigera of 

 D'Orbigny for such shells as the T. concentrica, lamellosa, roissyi, pectinifera, etc.; 

 thereby avoiding, at least in some degree, the palpable contradiction of the name 

 employed by Prof. M'Coy, the name Spirigera being evidently preferable to that of 

 Athyris. But this compromise has been criticised by many naturalists, who insisted 

 on the fact of the term Athyris having been originally and positively applied by its 

 originator to the T. concentrica, and also on the impropriety of the other appellation 

 to designate such shells as the T. tumida, herculea, e^c. M. Suess informs us,|| that 

 in 1851 he proposed the name Merista^ for the group comprising these latter shells. 

 I therefore abandon the proposition I made in 1853, and retain indifferently Athyris 

 of M'Coy or Spirigera of D'Orbigny for the T. concentrica ; and Merista of Suess 

 for the T. tumida, herculea, etc. I shall also follow Prof. King and Prof. Woodward 

 in placing those shells which have a punctate test, such as the T.ferita, adrieni, 

 serpentina, etc., in the subgenus Retzia of King; although at the same time it does 

 not appear to me that the characteristics and tendencies of these latter sufficiently 

 demonstrate the necessity of separating them from the group of the T. concentrica 

 {Athyris, M'Coy)." 



* Paleontologie Franrais ; terrains cretaces, Vol. iv, p. 357, 1847. 



\ Ann. and Mag. of Nat. His., Vol. xviii, p. 86, 1846. In this memoir Prof. King has 

 admirably described this remarkable process. 



J A Monograph of the English Permian Fossils (Pal. Soc), p. 137, 1843. Prof. Phil- 

 lips proposed to substitute the name C I eiothyr is for that of Dalman, Atrypa ; but he has 

 not made use of it in this work. Fig. and Desc. of the Pal. Fos. in the Cambridge Muse- 

 um, p. 196, 1852. 



§ British Paleozoic Fossils in the Cambridge Museum, p. 196, 1852. 



II Neues Jarhbuch, p. 62, January 1864. 



V Jahrb. d. K. Geol. Reichsanstalt, ii, iv, 150, 1851; mentioned also in Leonhard^s 

 Neues Jahrbuch, p. 127, 1854. 



