DEVONIAN AND OLD RED PERIOD. 145, 
principal forms. belong to the genera Phacops (fig. 88, a, c, 2), 
Flomalonotus (fig. 88, 6), Proetus, and Bronteus. The species 
figured above under the name of Phacops latifrons (fig. 88, a), 
has an almost world-wide distribution, being found in the 
Devonian of Britain, Belgium, France, Germany, Russia, Spain, 
and South America ; whilst its place is taken in North Ame- 
rica by the closely-allied Phacops rana. In addition to the 
Trilobites, the Devonian deposits have yielded the remains of 
a number of the minute Ostracoda, such as Fintomis (“ Cypri- 
dina”), Leperditia, &c., which sometimes occur in vast num- 
bers, as in the so-called ‘‘ Cyprvidina Slates” of the German 
Devonian. There are also a few forms of Phyllopods (Es- 
theria). Taken as a whole, the Crustacean fauna of the 
Devonian period presents many alliances with that of the 
Upper Silurian, but has only slight relationships with that of 
the Lower Carboniferous. 
Besides Crustaceans, we meet here for the first time with 
the remains of az7-breathing Articulates, in the shape of Jusects. 
So far, these have only been obtained from the Devonian 
rocks of North America, and they indicate the existence of at 
least four generic types, all more or less allied to the existing 
May-flies (Ephemeride). One of these interesting primitive 
insects, namely, Platephemera antiqua (fig. 89), appears to have 
measured five inches in ex- 
panse of wing ; and another 
(Xenoneura antiquorum) has 
attached to its wing the re- 
mains of a “stridulating- 
organ ” similar to that pos- 
sessed by the modern Grass- 
hoppers—the instrument, as 
Principal Dawson remarks, 
of “the first music of living : é 
2 Fig. 89.—Wing of Platephemera antigua. 
things that Geology as yet Devonian, America. (After Dawson.) 
reveals to us.” 
Amongst the Afollusca, the Devonian rocks have yielded a 
great number of the remains of Sea-mosses (Po/yzoa). Some 
of these belong to the ancient type Pre/odictya, which seems to 
disappear here, or to the allied Clathropora (fig. 90), with its 
fenestrated and reticulated fronds. We meet also with the 
graceful and delicate stems of Cerzofora (fig. 91). 
The majority of the Devonian /olyzoa belong, however, to 
the great and important Palzozoic group of the Lace-corals 
(Fenestella, figs. 92 and 94, Letepora, fig. 93, Polypora, and 
their allies). In all these forms there is a horny skeleton, of a 
K 
