1 86 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



staple beds south of Baggy. Thus these 2 genera and 8 species have 

 a wide range, due to their pelagic habit ; and regarding B. Urii, B. 

 Mulcus, and B. subc/lobatus as Carboniferous, 3 occur in the Lower, 

 3 in the Middle, and 5 in the Upper Devonian. 5 genera and 77 

 species are Continental and American. 



Cephalopoda. — Clymenia, Cyrtoceras, Goniatites, Nautilus, Ortho- 

 ceras, and Poterioceras are the 6 British Devonian genera with 60 

 species. Other foreign genera and 500 species are known. We can 

 hardly attempt comparison through such an extensive and widely 

 disseminated group. (The genus Goniatites is illustrated by 168 

 species, Clymenia 50, and Orthoceras 130 ; but Bactrites with 9 

 species, Cyrtoceras 60, Phragmoceras 12, and Trochoceras 6 species, 

 are not known in the British Devonians, besides many other smaller 

 genera.) Strange as it may appear, only one species occurs in the 

 Lower Devonian, Cyrtoceras bdellalites, Stutchb. ; yet this genus is 

 represented by 12 Middle and 2 Upper Devonian species. I am 

 disposed to believe that we have not in Britain any Lower Devonian 

 form at all, this single species from one locality being doubtful. 

 The 11 other forms are all Middle Devonian. 



Clymenia, the essential genus in the Devonian rocks of Britain 

 (and elsewhere), numbers 11 species, and all occur in the Upper 

 Devonian of Petherwin in North Cornwall. This genus is repre- 

 sented in Europe by 50 species, and, in the same stratigraphical 

 position, in the Upper division of the Devonian series. America 

 yields scarcely any Clymenice ; and no Clymenia occurs in the Devo- 

 nian rocks of North Devon, either Middle or Upper. 



Goniatites. — In the Upper Devonian of Petherwin this genus is 

 represented by G. biferus, G. linearis, G. subsulcatus, G. striatus, 

 and G. vinctus ; and 12 species occur in the Middle Devonian of 

 Torquay ; only 2 forms occur in the Upper beds of North Devon, 

 G. vinctus and G. spirorbis ; 4 of the Devonian species occur in the 

 Carboniferous rocks, G. carbonarius, G. ccecavatus, G. serpentimis, 

 and G. subsidcatus? As compared with the Carboniferous Gonia- 

 tites, the Devonian group is of slight importance ; in Britain alone 

 we have 72 Carboniferous species, and ] 60 Devonian species have 

 been described from European rocks, and only 6 or 8 from America* 



Cyrtoceras. — With one exception the 13 species of this genus 

 occur only in the Middle Devonian of Torquay. The single departure 

 from this is Cyrtoceras rusticum, the only Upper Devonian form in 

 the Petherwin beds ; this species is probably the C. arcuatum of Stein- 

 mcyer. 60 species occur in the Devonian rocks of Central Europe ; 

 and, as in the two genera before noticed, few are American. 



Orthoceras. — No species of Orthoceras has yet occurred in the 

 Lower Devonian beds, either of North or South Devon. The Middle 

 group at Torquay has yielded 8 species, and the Upper Devonian of 

 North Devon 13 ; and 4 of these North-Devon species pass to the Car- 

 boniferous south of Pilton and Barnstaple, viz. O. cinctum, O. lineola- 

 tum, O. striatum, and O. undulatum. 130 species occur in the Devo- 

 nian rocks of Ehenish Prussia and Central Europe, and less than 20 

 in America. Our Carboniferous rocks contain 47 species ; but, as we 

 have seen, only 4 species are common to the two formations. 



