DESCRIPTIVE REMARKS. |xiii 
vonian. We have figured on the Pl. xxxi., Murchisonia bigranulosa, 
fig. 6, and Huomphalus annulatus, fig. 7, both Middle Devonian species, 
Torquay group. 
The Cepnatoropa of the Devonian rocks, number according to the 
same authority, six genera including fifty-two species. Of the four 
principal genera Clymenia contains eleven species, Cyrtoceras thirteen, 
Goniatites ten, and Orthoceras fifteen. All the species of Clymenia 
occur in the Upper or Petherwin group, one of them only, C. levigata, 
appearing in the Middle Devonian, Torquay group. Of Cyrtoceras out 
of the thirteen species recorded, all of them except one, and that of 
doubtful occurrence, are found in the Torquay group. C. nodosum, 
Pl. xxxi., fig. 8, is a species confined to Middle Devonian. Clymenia 
striata, fig. 9, a, 6, is a genus belonging to the Mautilide in which the 
septa, 9 b, is simple or slightly lobed, it is almost entirely confined to 
the Upper Devonian. The genus Orthoceras is represented by one 
species in the Lower Devonian, six in the Middle Division (Torquay 
group), four of them continuing to the Carboniferous, ten in the Upper 
Devonian; one of these also continuing to the Carboniferous. The 
genus Nautilus is represented by two species, one of them in the 
Torquay group (Middle Devonian), the other in the Petherwin group 
(Upper Devonian). 
The Nucteoprancarata or Herrroprova of the Devonian rocks are 
of two genera, Bellerophon and Porcellia, the former include five species, 
three of them continuing into the Carboniferous rocks. 
The Preropropa of the Devonian rocks have only one representative, 
a species of Conularva not specifically named, it occurs in the I1fra- 
combe group of the Middle Devonian. 
The AnneELIDA are represented in Devonian rocks by the genus 
Tentaculites only, of which there are two species, both Middle De- 
vonian. 
The Crusracea of the Devonian rocks consist of six genera includ- 
ing thirteen species. ‘The small bivalve Carapaces of Entomis serrato- 
striata, Pl. xxxii., fig. 6, a, b, belonging to the Ostracoda, a very 
characteristic fossil of the Middle Devonian rocks of the Rhine, and 
the Upper Devonian of Belgium, is also found in the Petherwin group 
of the Upper Devonian in Cornwall. 
The Tritosires number twelve species included in five genera; 
Phacops latifrons, fig. 1, a, 6, is the most frequent in Middle and Up- 
per Devonian strata. The remarkable form of Harpes macrocephalus is 
shown at fig. 2, this fossil is in Britain confined to the Torquay group 
of the Middle Devonian, it also occurs in the same division on the 
Rhine. The large species Homolonotus armatus, fig. 3, is another re- 
markable Trilobite, more abundant on the Continent than in Britain ; 
it has been found in the Meadsfoot group of the Lower Devonian, and 
characterizes the Lower and Middle Devonian of the Rhine, and Lower 
Devonian of Belgium. Sronteus flabellifer, fig. 4, is a Middle Devonian 
type, in Britain confined to the ‘Torquay group, occurring also in the 
