652 PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. 



ing, then, that 235 species occur in South Devon (Table V.), we will 

 adopt them as our standard for comparison with the northern species 

 in the middle zone. We find, in aU, that 50 species of the known 

 235 are common to the two areas (vide Table YI.), which are related 

 by a marked and peculiar facies, one distinctly characteristic of, and 

 identical with, the Middle Devonian, or Eifelian and Stringocepha- 

 lenkalk, of the Rhenish provinces &c., which is especially borne out 

 by the Brachiopoda and Coelenterata : 21 species of the former, out 

 of 67 in South Devon, are common to the Middle Devonian of it 

 and the North; and 17 of these occur in European areas. 



This close approximation in the number of identical species is 

 most significant of their synchronous deposit ; and similarity of con- 

 ditions is evidenced by the structure of the rock-masses in aU the 

 areas. Comparison among the corals shows diiferent results, so far 

 as numbers are concerned. Of the 50 species known in South Devon 

 18 are also common to it and the North ; and of these 18, seven are 

 found in the Western European Devonians, no species living on to 

 the Carboniferous period. The grand development of limestone in 

 South Devon wiU fully account for the greater number of known 

 species of corals over that of the northern area, added to its being 

 also more extensively worked for economical purposes ; and the 

 rocks of the southern area have been more industriously searched 

 and examined by many able geologists*; and now, under the patient 

 research of a few good observers t, the northern slates and lime- 

 stones are abundantly yielding species identical with those of the 

 south. One bivalve only occurs common to the two, Megalodon 

 cucullatum; two univalves, Acroculia vetusta and Euomphalus ser- 

 pens ; the sponge Stromatopora concentrica, and four Polyzoa, with 

 Phacops (Trimerocephalus) Icevis, and Tentaculites annidatus, com- 

 plete the 50 common or connecting species ; 8 of these 50, chiefly 

 Brachiopoda, recur in the Carboniferous series. Want of more com- 

 plete evidence prevents our comparing the Middle Devonian of Corn- 

 wall with either area ; but of the known species only 4 occur as com- 

 mon, viz. Athyris concentrica, Atrypa desquamata, Spirifera speciosa, 

 and Favosites cervicornis. In Table lY. p. 640, is given the whole 

 Middle Devonian fauna of North Devon and West Somerset, in which 

 71 species are shown to be distributed through that area ; to these 

 71 I now adjust and compare those known to occur in the Rhenish, 

 Belgian, and French areas, so as to correlate them, through their 

 fossils, with our North-Devon types, and to show their intimate 

 relation, connexion, and identity; for most of them are cognate 

 species. 



In Table Y. it is shown that 34 species are common to North Devon 

 and Europe, and that chiefly as before, through the two classes, 

 Actinozoa and Brachiopoda, 10 species of corals and 16 species of 

 Brachiopoda occurring in our own and one or other of the European 

 Devonian areas, whereas only one Lamellibranch, Megalodon cucul- 



* Mr. Godwin-Austen(G-eol. Trans.), Phillips, Pengelly, Sedgwick &Murchi- 

 son, Lee, Vicary, &c. &c. 

 t Mr. Yalpy, Mr. Hall, Rev. W. Mules, the Rev. H. H Winwood, &c. 



