BRACHIOPODA. 79 



aucune fissure, sur la surface ni de I'uue, ni de I'autre valve. Ce fossile n'est 

 done pas une Discina. Mais nous observons, au contraire, la trace d'une per- 

 foration sur le bord. Elle est indiquee par une petite cylindre de la roche, qui 

 la injectee et qui fait saillie sur le contour." Barrande, loc. cit. 

 Type, Paterula Bohemica, Barrande. Etage D. 



The position of this genus, as far as it rests upon the character of the pedicle- 

 aperture, appears to be near that of Schizobolus, while the narrow internal 

 septa diverging from the beak suggest relationship to 

 Leptobolos. The nature of the shells is not well under- 

 stood, but it is evident, from the description and figures 

 given by the author, that it is allied to those forms in 

 which the pedicle-passage is in the first stages of its tran- f'°- %,^t7^^J^^""'"'- 

 sition from the intermarginal obolelloid condition, to the supramarginal phase 

 developed in Siphonotreta, etc. 



In the "General Summary the British Fossil Brachiopoda" (p. 391), Mr. 

 Davidson has referred to this genus his species Discina ? Baldetchensis, a form 

 occurring in great numbers in the Llandeilo and Upper Caradoc, and though 

 like the Bohemian species in the character of its broad marginal rim, no evi- 

 dence is afforded of the pedicle or internal characters. We have received from 

 Mr. H. M. Ami the only American specimens which we should feel disposed to 

 refer to this genus. An enlarged figure of a gutta-percha impression taken 

 from the best of these, is given on Plate IV k, fig. 1, and shows the conspicuous 

 rim, the pedicle-notch, and the radiating muscular impressions taking their 

 origin about an intramarginal callosity. This shell is from a black limestone 

 in the city of Quebec, currently referred to the age of the Quebec group. 



