DAVIDSON — ON BRITISH CARBONIFEROUS BRACHIOPODA. 



57 



without that success I had anticipated, I must leave the matter as an 

 open question, notwithstanding the advantages I had of being able 

 to examine the original specimens or fragments upon which the so- 

 termed Irish species ? have been founded. 



Crania. — Three species have been retained ; but of these C. 

 quadrata is the only satisfactorily determined species. Of Crania ? 

 trigonalis I have never seen more than the original type, and it is still 

 uncertain whether it is a Brachiopod, notwithstanding that we are 

 acquainted with several similarly striated or costated species in the 

 rocks of other periods. Of Crania ? (Patella) Bychholtiana de Koninck 

 = C. vesicularis, M'Coy, I am acquainted with but a single Irish 

 specimen; but the shell would appear to be less rare in certain Derby- 

 shire localities. It would be very desirable however to procure more 

 specimens of both C. trigonalis, and C. BycJclioltiana, and especially 

 those showing the interior. 



Discina. — Two species only have been retained, viz., D. nitida and 

 D. Davreuxiano, de Kon. ; but as of this last but a single example has 

 been found by Mr. J. Wright, in the limestone of Little Island, in Ire- 

 land, it is therefore here doubtfully recorded. I may also mention that 

 I am strongly impressed with the idea that the Permian D. Koninchii 

 cannot be specifically separated from the Carboniferous D. nitida. 



Lingula. — The many so-termed species are reduced to four, viz., 

 Lingula squami/ormis, (which has sometimes attained upwards of one 

 inch and a half in length). L. mytiloides, a more elongated species, 

 L. Credneri, which may possibly be a variety of L. mytiloides, and L. 

 Scotica which is separable from all the others by its tapering beaks and 

 peculiar external sculpture. 



Having thus briefly exposed the present state of my researches in 

 connection with British Carboniferous Brachiopoda, as well as men- 

 tioned some of the difficulties which still beset my mind with reference 

 to the positive value of certain so-termed species, and exposed my 

 ignorance as well as the absolute necessity for much further research, 

 let us cast a rapid glance on the Brachiopodous life during the depo- 

 sition of contemporaneous (?) Carboniferous rocks in other parts of the 

 world, in order to ascertain whether our British fauna in this respect 

 was not to a certain extent universally represented. In Europe we 

 find that where carboniferous strata prevail a vast majority of the same 

 species exist ; and as those of Belgium, France, Russia, etc., are 

 already so well known, from the researches of several distinguished 

 paleontologists, we will at once proceed to India, where out of twenty- 

 five or twenty-six species of Carboniferous Brachiopoda hitherto 

 determined, some fourteen or fifteen were found (on an examination 

 I have recently made) to be specificaly identical with British forms of 

 Spirifera striata, 8. lineata, S. octoplicata, (cristata,) Athyris Boyssii, 

 A. subtilita, Betzia radialis, Bhjnchonella pleurodon, Streptorhynchus 

 crenistria, Orthis reswpinata, Productus st/riatus, P. costahis, P. semi- 

 reticulatus and P. longisjjinus, and a further research in these distant 

 regions will no doubt bring to light a larger number of common 

 species. 



vol. iv. H 



