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700 STRATIGRAPHICAL GEOLOGY. — [Boox VI. 
gasteropod nor cephalopod and only 21 species of brachiopods. Traces 
of fish remains have been obtained among them in the form of bones and 
coprolitic débris. So far as observation has gone, not a single Silurian 
species has been certainly detected in the Devonian rocks of Britain, 
with, according to Mr. Etheridge, the sole exception of the long-lived 
and universally diffused Atrypa reticularis. There can be no doubt, how- 
ever, from the meagre list of fossils from the Lower Devonian rocks of 
Devon and Cornwall, that either the conditions for the existence or 
those for the fossilization of the early Devonian fauna must have been 
singularly unfavourable in the south-west of England. It would be rash 
to argue as to the extinction of the Silurian fauna from the unsatis- 
factory evidence of these rocks. 
Mippie.—As above remarked, this is the great storehouse of Devonian 
fossils in the south-west of England. In this fauna, as tabulated by Mr. 
Etheridge, there are 8 protozoa, including 5 species of Stromatopora, of 
which S. concentrica and S. placenta are characteristic; 24 genera and 48 
species of actinozoa, among which the corals Acervularia (7 species), 
Alweolites (4), Cyathophyllum (12), Favosites, Pleurodictyum, and Petraia are 
conspicuous; 6 genera and 12 species of crinoids (Hexacrinus, Cyatho- 
crinus, Cupressocrinus, &c.) ; a pteropod ( Tentaculites annulatus); 5 genera 
and 6 species of crustaceans, which are all trilobites (Phacops granu- 
latus, P. latifrons, P. punctatus, Bronteus flabellifer, Cheirurus articulatus, 
Harpes macrocephalus). The bryozoa are represented by 6 genera 
and 7 species. The brachiopods are the most abundant forms, 
numbering at present 23 genera and 80 species out of a total British 
Devonian list of 26 genera and 116 species. Among them are Athyris 
concentrica, A. lachryma, Atrypa reticularis, A. desquamata, Camarophoria 
rhomboidea, Cyrtina Lemarlii, Orthis striatula, Rhynchonella acuminata, R. 
pugnus, Pentamerus brevirostris, Spirifera Vernewili (disjuncta), Stringo- 
cephalus Burtini, Uncites gryphus, &c. The lamellibranchs are poorly 
represented, 13 genera only occurring, many of them represented by only 
one species; the most common genera being Pterinea, Aviculopecten, and 
Megalodon. The gasteropods are likewise present in but small numbers 
and variety ; 12 genera and 36 species have been enumerated. Of these 
species, 5 (Acroculia vetusta, Lowonema rugiferum, L. tumidum, Murchisonia 
angulata, and M. spinosa) survived into the. Carboniferous period. The 
cephalopods are represented by 5 genera, the most abundant specifically 
being Cyrtoceras (12 species), Orthoceras (8), and Goniatites (12); one 
species of Nautilus also occurs. Of the total list of fossils a large propor- 
tion is found in the Middle Devonian rocks of the continent of Europe. 
Uprrr.—From the calcareous portions of the Petherwin and Pilton 
beds of Cornwall and Devon a considerable number of fossils has been 
obtained. Among the more characteristic of these we find 11 species of 
the coiled cephalopod Clymenia (C. undulata, C. levigata, CO. striata), a 
number of species of Goniatites (G. intumescens, G. multilobatus, G. retrorsus, 
G. auris), Bactrites Schlotheim, the trilobites Phacops granulatus and P. 
latifrons, the small ostracod Hntomis (Cypridina) serrato-striata, the brachio- 
pods Spirifera Verneuili or disjuncta, Strophomena rhomboidalis, Chonetes har- 
drensis, Productus subaculeatus, and the lamellibranch Cucullea Hardingii. 
Some traces of fishes, referred to Coccosteus, have been recently found. 
The Marwood and Baggy Point beds have also yielded traces of land 
plants, such as Knorria dichotoma and Palzopteris Hibernica, the latter fern 
being common in some parts of the Upper Old Red Sandstone of Ireland. 
