676 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



contain the nineteen North-Devon species, are wholly unaccounted 

 for in Mr. Jukes's paper, either upon the hypothesis of the fault or 

 anticlinal. Neither the rocks nor the fossils occur to the south 

 of the Pickwell range, or Upper Old Red Sandstone ; and the great 

 series of slates of Mortehoe, Lee, Ilfracombe, and Combe Martin, 

 with the Hangman grits below, hold a distinctive and intermediate 

 position, which his hypothesis cannot account for, even upon phy- 

 sical grounds ; and the entire fauna of the Ilfracombe group has 

 also to be accounted for, and correlated with that of Baggy and 

 Marwood ere any relation can be proved to exist. There is not, 

 however, the least doubt that the whole Middle group is a well- 

 determined one, and exists below the Pickwell-Down or Upper 

 Old Red Sandstone series in North Devon. 



Echinodermata. — Of the ten known genera, three are common ; 

 and of the twenty-one species, only four occur in the Carboniferous, 

 one of which, Cyaihocrinus pinnatiis, I much doubt. 



Annelida. — No comparison, 



Crustacea. — Six genera and thirteen species are known in, and are 

 entirely confined to, the Devonian rocks of North and South Devon. 

 As before mentioned, both families, genera, and species are pecuhar 

 to them in the British and the three Continental areas. 



Polyzoa. — The eight genera and twelve species known show nearly 

 50 per cent, common, viz. four genera and seven species. I give 

 them, because at present they occur in most lists ; but I believe that, 

 when carefully examined, this group will require entire recon- 

 struction, both for the Devonian and Carboniferous rocks. 



Brachiopoda. — We know of twenty-five genera and ninety-nine 

 species in the British Devonian rocks; eleven of the genera and 

 fourteen species pass up to the Carboniferous series through the 

 Carboniferous Slate or Lower Limestone Shales. Except through the 

 genus JRhyncIionella, which has four species common, there is only 

 one representative species in each of the remaining genera — a signi- 

 ficant fact and to be noted in this prolific group, in which the species 

 are usually so great numerically. 



LamellibrancJiiata. — Out of the twenty genera and fifty-seven 

 Devonian species, eight species only, through the two groups 

 (Monomyaria and Dimyaria) unite the two systems; through the 

 Curtonoti and CucuUcem there may be two or three more. With 

 relation to the Devonian series, however, we have much to learn 

 in this class, which in the Carboniferous rocks numbers 330 species. 



Gasteropoda. — Only twelve genera are known ; but their specific 

 value is numerically greater than that of the Lamellihrancliiata, 

 there being 46 species of them ; only six of the former and eight of 

 the latter are known above the Upper Devonian beds. 



CepTialopoda. — This pelagic class is represented in the Devonian 

 rocks by six genera (all Tetrabranchiata). I have previously noticed 

 (p. 650) their singular local distribution through the large assem- 

 blage of species in the genera Clymenia and Cyrtoceras. We have in 

 our British Middle and Upper Devonian beds fifty-four known forms, 

 nine only of which are common to the succeeding Carboniferous, and 



