94 REPORT — 1860. 



Table, that, taken together, the five areas have yielded 347 species of fossils belong- 

 ing to 97 genera and 49 families, of 9 classes of animals; namely, three classes of 

 the subkingdom Radiata, one of Articnlata, and five of Mollusca; hence 15 of the 

 24 classes into which the existing animal kingdom is commonly divided are totally 

 unrepresented in the series, as is the entire vegetable kingdom also. 



It is scarcely necessary to remark that the fossils of Devon and Cornwall do not 

 fully represent the organisms of the Devonian age, as six other classes — Pisces, 

 Pteropoda, Cirripedia, and Annelida amongst animals, and Cellulares and Monoco- 

 tyledones amongst plants — have been found in rocks of this age elsewhere ; and of 

 these the last and first two have been met with in British localities. 



The most important class numerically is Brachiopoda, to which 108 species belong; 

 that is 31 per cent, of the entire series. The families and genera of Cephalopoda are 

 richer in species than those of any other class, averaging 16 for each family and 10 

 for each genus. 



The most striking fact in this connexion, is the abundance of Brachiopoda and 

 Cephalopoda, and the paucity of Lamellibranchiate and Gasteropod species, as com- 

 pared with the numerical rank of the same classes in the existing British fauna; this 

 will, perhaps, he most strikingly exhibited by the following Table : — 



Table II. 



Devonian Mol- Existing 



lusca of Devon British 



and Cornwall. Mollusca. 



Bryozoa 42 72 



Brachiopoda 410-5 15 - 5 



Lamellibranchiata 186 359-5 



Gasteropoda 179- 521-5 



Cephalopoda 182-5 31-5 



1000 1000 



which has been thus computed ; in the left-hand column the aggregate number of the 

 species of fossil Mollusca found in Devon and Cornwall has been put=1000, and the 

 numbers belonging to each class equated to this; the right hand column has been 

 formed on the same principle, and is based on the data given by Forbes and Hanley 

 in their ' History of British Mollusca.' 



It appears then that within existing British seas, the Lamellibranchiates are about 

 twenty-four times more numerous, specifically, than the Brachiopods, whilst within 

 what may be called the same area, the latter were to the former during the Devonian 

 period somewhat more than as 2 to 1 ; that is, they were then 50 times more abun- 

 dant than at present in comparison. with the other great class of Acephala. In like 

 manner it is seen that, relatively to the Gasteropoda, the Cephalopoda were, in this 

 early age of our planet, seventeen times more numerous than now. It may be added 

 that, within the district under notice, the registered species of Devonian Brachiopoda 

 and Cephalopoda absolutely, and in a high ratio, exceed those belonging to the same 

 classes within existing British seas. 



The five columns of Table I. headed "Peculiar to," and distinguished from one 

 another by the initials of the five areas, show the number of fossil species which, so 

 far as England is concerned, are peculiar to each ; from which it appears that 296 

 species are peculiar to one or other of them, leaving no more than 51 distributed 

 amongst them. Lower South Devon monopolizes no fewer than 191 species in this 

 way, whilst Lower North Devon is equally remarkable for its fossil poverty. 



Five areas, taken two, three, four, and five together, are capable of being formed 

 into twenty-six different combinations. Not a single species is common to the 

 five areas, and only one, Cyathophyllum celticum, is found in each of four of them. 

 The well-known coral Favosites cervicomis is the only fossil found in each of the 

 three contemporary deposits of Lower North and South Devon and Cornwall. Of 

 two areas only, Upper North Devon and Upper Cornwall have the greatest number — 

 fourteen — in common.* 



* See in Table I. the ten columns headed " Common to," and distinguished by combina- 

 tions of initials of two or more areas. 



