432 Mr. T. Davidson on the Brachiopoda. 



This arrangement, although still imperfect in some respects, 

 will I hope be found to possess advantages over the one pub- 

 lished in 1853, being more simple and perhaps nearer to the 

 truth. In the first place, we have got rid of all the subfamilies ; 

 the genera are located into eight families ; that of Calceolida, 

 which formed the ninth, being suppressed, on account of the 

 great uncertainty still existing, as to whether or not Calceola is 

 a true Palliobranch, M. Suess seems to believe that it is not 

 so ; but as much doubt remains as to where the shell should be 

 located among the Mollusca, we have left the name pi*o vision ally 

 in the Table, and must refer the reader to the German edition 

 for more ample details on this point. Mr. S. P. Woodward, in 

 whose knowledge on all appertaining to the Mollusca the greatest 

 reliance may be placed, has also adopted eight families in his 

 excellent ' Manual of the Mollusca,' and the only difference in 

 opinion between us is whether the fourth family should be 

 termed Strophomenidae or Orthidae. I adopted the first name 

 simply on account of priority, but quite agree that my friend is 

 right when he states that the names of families should be formed 

 from those of the typical genera; the only question which might 

 arise in the present case being, which of Orthis or Strophomena 

 is in reality the typical genus. 



Among the genera and subgenera we have proposed the fol- 

 lowing changes : — 



1. Terebratulidae. Kraussia, Magas, Bouchardia and Mor- 

 risia have been placed among the subgenera of Terebratella, 

 as this last may be considered the great typical genus to which 

 the subgenera mentioned ai-e more nearly related than to that of 

 any other group. Trigonosemus we have consented to erase on 

 M. Suess's proposition, as it possesses all the essential internal 

 characters of Terebratella, of which it is only a synonym ; the 

 largely developed cardinal process of T. elegans is not found in all 

 the other forms which had been located with Ti'igonosernus, nor has 

 the beak always the peculiar shape of the last-named species. Lyra 

 (Cumberland) = Terebrirostra, D'Orb., appears to be composed 

 partly of shells belonging to Terebratella and perhaps Wald- 

 heimia, and as the greater or lesser length of the beak is of very 

 little generic importance among the Brachiopoda, that section 

 can be advantageously dispensed with. Stringocejohalus and The- 

 cidium have also been admitted into the present family, which 

 seems to be their most natural resting-place. 



2. Spiriferidae. The changes we have made in this family con- 

 sist in re-establishing Prof. M'Coy's genus Athyris as typified 

 by such shells as T. concentrica, lamellosa, &c., and adopting the 

 subgenus Merista, Suess, for T. Herculea, scalprum, tumida, and 

 other such shells. This last mode has been adopted by Mr. S. 



