216 BRITISH CARBONIFEROUS BRACHIOPODA. 



1844 in the ' Synopsis of the Carboniferous Fossils of Ireland,' PI. xxii, fig. 21, is nothing 

 more or less than an elongated malformation of Athyris ptano-sulcata ! a discovery entirely 

 due to my zealous friend Mr. J. Wright, of Cork, who having obtained the typical 

 specimen (formerly in the collection of Dr. Haines), and a number of similar malformations 

 found in the limestone near Cork, has left no possible doubt in the matter. (PI. LI, 

 11 and 11V) 



It is well known that the carboniferous fossils of the South of Ireland are usually much 

 distorted by pressure or cleavage, and that the mere form is of but little specific value ; 

 and in illustration of this I have represented four specimens of T. hastata found near Cork 

 (PL XLIX, figs. 1 3 to 16) which show what extraordinary modifications the same species 

 may assume under similar circumstances. 



It is not in my power at present to say what may have been the parent form from 

 whence all these modifications of T. hastata have been derived. We shall probably trace it 

 hereafter in the Devonian or even Silurian periods ; but I am also quite aware that the 

 generality of Palaeontologists are not yet sufficiently imbued with the absolute necessity of 

 enlarging the circle of variation to be permitted to a species, and will naturally say that 

 " they must totally dissent from my putting such a lot of shells into a single species." 

 I think, therefore, that should Palaeontologists hereafter consider it desirable to merge the 

 whole British Carboniferous Terebratula into T. hastata that the varietal designations of 

 Gillinyerisis, Sacculus, and Vesicularis, might perhaps be retained to denote certain modi- 

 fications in its shape. 



Athyris, or Spirigera. 



In external shape the species of this genus approach more to Terebratula than to any 

 other genus, and therefore in a good or natural arrangement it should precede Spin/era. 

 Nine species of Athyris have been provisionally retained from among the many synonyms, 

 while the value of A. ylobularis and A. squamiyera may still require confirmation ; for of 

 both these shells the material at my command has been very scanty : and it is even 

 uncertain whether the identification with A. squamiyera (de Koninck) be correct. 



Athyris ambigua (p. 77). Plate XV, figs. 16—22 ; and Plate XVII, figs. 11—14. 



The muscular impressions of Athyris have been represented in Athyris undata (a Devo- 

 nian species), but not in quite so precise a manner as could be desired, as seen on some 

 silicified internal casts of A. ambiyua from the carboniferous limestone of Bakewell 

 (Derbyshire), in the Museum of Practical Geology, and of which two enlarged illustrations 

 will be found in PI. XVII of the present Monograph. I have also ascertained (since the 

 publication of my description of this species) that the spiral processes, and their interme- 



