452 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 22, 



It must be admitted that the connexion between the rocks of the 

 Liskeard and Looe -river range, on the one hand, and those of 

 South Petherwin, on the other, by means of their fossil contents, 

 does not appear at first sight to be very strong; but the lists of 

 species compared are small, and of that of the southern areas one- 

 third of the species are in common. Moreover it must be remem- 

 bered that nearly the whole of the Petherwin fossils come from the 

 single locality of Landlake ; a few occur in the quarry at South 

 Petherwin ; but the other hmestone deposits are unfossihferous, a 

 very few only occurring in the slates above them, and the continu- 

 ation of the range to the coast affords only the following species : — 

 Petraia CeltlccCy Phacops latifi^ons* , Pterinea subi^acliata* , Stroplialosia 

 productoides* , BliynchoneUapleurodon, Spinfera disjunctaf, and var. 

 gigcis, and inornata*, and S. speciosci*. With the exception of the 

 latter, these are all Petherwin fossils. Nevertheless we arrive at 

 the conclusion that the Petherwin beds are not high up in the series, 

 even from these data (independently of stratigraphical considerations), 

 from their palseontological connexion with the higher group being 

 so much less strong than it is with the middle group. 



The unequal distribution of organic remains above alluded to in 

 reference to the Landlake quarry appears to obtain very generally 

 throughout the Devonian rocks of South Devon, although not always 

 to the same extent ; and it is, perhaps, what might be partly expected 

 when we take into consideration the isolated position of many of 

 these calcareous deposits ; for whether we assume their coral-reef 

 origin or not, they are still patches separated by intervals, more or less 

 considerable, of, probably, muddy sea bottoms. Mr. Godwin- Austen, 

 long ago, drew attention to this local association of genera and species:^, 

 one form of Coelenterata prevailing in one locahty, while another is 

 the dominant species in a neighbouring one. Some of these calcareous 

 deposits appear to contain little else than one or two species of Corals 

 and a few Amorphozoa. Others teem with Brachiopoda like those of 

 Woolborough and Barton. At the same time the limestones of Wool* 

 borough, Ogwell, and Barton have been, no doubt, more diligently 

 searched, especially Woolborough, and for the reason, as Mr. Godwin- 

 Austen states, that the fossils at that quarry are extracted more easily 

 and in better condition than at any other, and it is therefore a fa- 

 vourite spot of collectors. But the Woolborough colony is in fact 

 no less remarkable than that of Landlake, and has alone afforded 

 139 species. Woolborough and Barton are equally rich in Brachio- 

 poda, viz. 38 species, but only 26 species are common to the two 

 localities. Woolborough has 20 Brachiopods in common with Dart- 

 ington, 19 with Hope's jS'ose, 18 with Plymouth, and 13 with Ilfra- 

 combe. Barton has 18 Brachiopods in common with Dartington, 

 Hope's Nose, and Plymouth respectively, but only 10 with Dfra- 

 combe §» Nevertheless all these localities are in Middle Devonian 



* Mus. Geol. Soc. t Mus. Pract. GeoL, Jermyn St. 



X L. c. p. 465. 



I Vide Mr. Pengelly's tables, Trans, of the Devonshire Association for the 

 Advancement of Science, Literatvire. and Art. 1807. 



