Page:A Treatise on Geology, volume 1.djvu/173

the fossils of the Devonian and Caledonian types of old red in Britain we have a pretty full catalogue of invertebrate.

	No. of Species.
Polypiaria	34	Of these, 25 species are also found in the Silurian system; and 51 in the carboniferous limestone series, 57 occur in the Devonian strata of the Eifel, a limestone district wkich corresponds with the Plymouth group.[1]
Crinoidea	16
Lamellibranchiata	46
Brachiopoda	83
Gasteropoda	36
Cephalopoda	44
Heteropoda	7
Crustacea	9
	——
	275
	——

As characteristic Devonian forms we may mention—

1. Cystiphyllum damnoniense.—a. Lamellæ,
2. Strombodes vermicularis.—a. Lamellæ.
3. Leptæna nodulosa.
4. Calceola sandalina.
5. Palaeopora pyriformis.
6. Strigocephalus Burtini.
7. Cyrtoceras tredecimale.—a. Aperture.
8. Clymenia laevigata.—a. Aperture.
9. Brontes flabellifer.

The fishes of the old red sandstone which have been systematized by Agassiz, and described with much effect by Miller^[2], are very characteristic of this palæozoic period. The classification of Agassiz, presented to the British Association in 1843, includes 63 British species, viz.:

Placoid.—Ichthyodorulites 6; Cestraciontes 1.

Ganoid.—Lepidoid 33; Sauroid 13; Coelacanthoid 10.

Some of these, as well as a considerable number of the invertebrate, occur also in Russia, the only region which presents something like a fair example of the

1. Phillips in Palaeozoic Fossils of Devon and Cornwall. See also the earlier investigations of Lonsdale (Geol. Trans.), and the later researches of M'Coy (British Palaeozoic Fossils).
2. The Old Red Sandstone.