38 
TUE GEOLOGIST. 
five Carboniferous forms, ten Silurian, eight common to Silurian and 
Carboniferous, and ninety-seven — slightly more than half — peculiar 
to Devonshire.* At present (confining ourselves also to South 
Devon) the catalogue gives a total of two hundred and twenty-six, 
of which thirty-four are Carboniferous, six Silurian, and a hundred 
and eighty-six peculiar to the district ; or putting the totals at 
each period = 1000, and equating the other numbers to this, the 
figures stand as in the following table, and show a decided advance 
Devonian- ward. 
TABLE VIII. 
1846. 
I860. 
Silurian 
53 
26-5 
Carboniferous 
395 
150-5 
Silui'ian and Carboniferous 
42 
00 
510 
823-0 

1000 
1000 
Doubtless the fact that the Carboniferous forms so greatly out- 
number the Silurian has a meaning. Does not this greater organic 
affinity betoken a closer connection with the more modern than with 
the more ancient period ? Is it not an intimation that the lowest 
beds of Devonshire do not constitute the basement of the Devonian 
system ? — that the county has an ample development of Upper and 
Middle, but not of Lower Devonian rocks ? 
Hitherto we have accepted the opinion of Professor Sedgwick re- 
specting the Petherwin and Barnstaple beds ; namely, that they are 
strictly contemporary, and constitute the uppermost division of the 
Devonian system. It may, perhaps, be well, before closing this 
paper, to go somewhat fully into the arithmetic of the question. 
A glance at Table IX. will show the number of fossil species and 
genera found in the two areas. 
TABLE IX. 
Petherwin. 
Babnstaplb. 
Gen. 
Spec. 
Gen. 
Spec. 
3 
3 
1 
1 
Echinodermata 
1 
1 
4 
6 
Crustacea 
2 
2 
1 
1 
2 
2 
3 
3 
Brachiopoda 
7 
20 
8 
26 
Laniellibranchiata 
7 
14 
8 
21 
6 
9 
7 
10 
5 
21 
2 
8 
Totals 
33 j 72 
34 
76 
* Memoirs Geol. Survey, vol. i. p. 96. 
