5G 



PALAEONTOLOGY. 



chonella (Fisch.) Their shells do not exhibit the punctate 

 structure under a magnifying-glass, and they have no internal 

 skeleton to support their arms, which in the recent species are 

 coiled up spirally, and directed towards the concavity of the 

 smaller valve, like the spires of the extinct Atrypa (fig. 12, 7). 



Fig. 12. 

 Brachiopoda. 



1. Trigonosenius Palissyi, Woo.dw. ; U. Cretaceous, Ciply. 



2. Stringoceplialus Burtini, Defr. ; Devonian, Eifel. 



3. Spirifera striata ; Carbonife rous, Britain. 



4. Cyrtia trapezoidalis ; U. Silurian, Dudley. 



5. Athyris Roissyi, Ler. ; Carboniferous, Ireland. 



6. Uncites grypbus, Schl. ; Devonian, Belgium. 



7. Atrypa reticularis, L. ; U. Silurian, Malvern. 



8. Pentamerus laevis ; Caradoc S., Salop. 



Of the" three living species of RJiynchonella, one is found 

 throughout the Arctic Seas, a second in New Zealand, and the 

 third at the Feejees (?). The fossil species exceed 250, and 

 are found in all parts of the world; those from the palaeozoic 

 strata may prove distinct from the rest, since the permian 

 species are known to be provided with large internal processes 

 (Camarojjhoria, King). Casts of these shells are frequently 

 impressed with the narrow and angular pallio-vascular impres- 

 sions. The extinct genus Atrypa differs from Rliynchonella 



