500 Lohley — Distribution of British Brachiopoda. 



Passing over several genera wbicli have comparatively short 

 ranges, we find the well-known Terebratula commencing in the 

 Middle Devonian, having a great development in Oolitic and Cre- 

 taceous strata, and continuing to the present time. 



We next find Merista and Uncites with one species each in the 

 Middle Devonian, Camaroplioi'ia next, and then Davidsonia, of which 

 one species only has up to the present time been discovered in 

 British strata. 



Productus has a very remarkable range and distribution. The 

 first species we find in Middle Devonian, three in Upper, and no 

 less than 41 in Carboniferous Limestone; after which only two 

 species appear, and these are in the Permian Magnesian Limestone. 



StringocepJialus and Bensselceria, two genera with only one species 

 to represent each, are also in the Middle Devonian. 



Strophalosia we find in Upper Devonian strata, and this is the last 

 of the Paleeozoic Brachiopods. 



Li Mesozoic rocks, Thecidium, Zellania, Argiope, Terebratulina, and 

 Waldlieimia all commence in the Lias, Terehratella in the Great 

 Oolite, and Megerlia, Terehrirostra, Trigonosemus, and Magas in Cre- 

 taceous formations, the last-named genus not being found lower than 

 the Chalk; and as no genus is known to commence its range in 

 Cainozoic strata, Magas may be considered, according to our pre- 

 sent knowledge, the newest of British fossil Brachiopoda. 



Eleven genera are represented by species now living in the seas 

 of our globe, and are therefore recent as well as fossil genera. Of 

 these Discina, Lingula, Crania, BhyncJionella, and Terebratula, range 

 upwards from Palaeozoic rocks. 



The genera Leptcena, Spirifera, and Spiriferina, range from Palseo- 

 zoic into Mesozoic, but do not reach Cainozoic strata, while there are 

 no less than twelve genera, each of which is characteristic of a single 

 formation, or minor group of strata. 



The following is a list of the species of these twelve genera with 

 the names of the formations, or groups, characterised by them. It will 

 be seen that only two of these genera, Orthisina and Orbictdoidea, 

 are represented by more than one species each. 



Kutorgina cingulata^ Bill., Primordial Silurian. 

 Acrotreta Nicholsoni, Dav., Llandeilo. 

 Orthisina ascendens. Pander ) ^ j 



„ Scotica, McCoy l^^'^^^^- 

 Orbiculoidea Beckettiana, Dav. \ -nr i u 



„ Forbesii, Dav. / 



Nueleospira pisum, Sow. sp., "Wenlock. 

 Merista plebeia, Sow., Middle Devonian. 

 Uncites gryphus, Schl., Middle Devonian. 

 Davidsonia Verneuilii, Yon Buch, Middle Devonian. 

 String ocephalus Burtini, Def., Middle Devonian. 

 Rensselceria stringiceps, Roem, Middle Devonian. 

 Terehrirostra lyra, Sow., Upper Greensand. 

 Magas pumila, Sow., Chalk. 



Thirty genera are essentially Palaeozoic, and eight genera have 

 not been found in any other than Mesozoic strata, though four of 

 these have living representatives, while not one genus can be con- 

 sidered characteristic of Cainozoic strata. 



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