SUMMARY OF THE CONTENTS OF THE CATALOGUE. XXX1X 
Conularia, and Bellerophon, and a species of Orthoceras, which at present is the oldest 
known form of the Cephalopodous group of Mollusca. 
The Arenig or Skiddaw group, which is classed as the upper part of the Middle 
Cambrian, or as forming the base of the Upper Cambrian, contains many species of Grap- 
tolitide, belonging to the genera Graptolites, Diplograpsus, Phyllograptus, Didymograpsus, 
Dichograpsus, Tetragrapsus, and Dendrograpsus, a few worms, some genera of Trilobites of 
which, species of Calymene, Aiglina, and Ogygia, are the most abundant, together with a 
few Brachiopoda, Lamellibranchiata and Pteropoda. 
The Upper Cambrian comprising the Lower, Middle and Upper Bala groups, is represented 
in the collection by a numerous fauna. There are many species of Graptolites, Corals 
(both Tabulate and Rugose), Brachiopoda, and Trilobites, which latter here attain their 
maximum developement; together with a less number of species of Lamellibranchiata, 
Gasteropoda, Pteropoda and Cephalopoda, and some Crinoids and Starfishes (Protaster, 
Paleaster). 
Silurian. 
The May Hill Sandstone or upper Llandovery is represented by some species of Corals 
belonging to the genera Favosites, Heliolites, and Petraia; a few Annelids and Trilobites: 
the Brachiopoda, however, are the most abundant, whilst the species of Gasteropoda, Lamel- 
libranchiata and Cephalopoda are but few in number. 
The Lower Wenlock group. In this, as in the preceding group, the Graptolites have 
diminished in number, and the Corals, Echinoderms and Trilobites have but few repre- 
sentatives; but, as in the preceding period, the Brachiopoda are most abundant, the Cephalo- 
poda also comprising a large number of species. 
The Wenlock group contains a rich fauna: the Bryozoa and <Actinozoa, both Tabulate 
and Rugose, are here numerically abundant. The Crinoids and Cystideans contain many 
species, as also do the Trilobites (40), Brachiopoda (82), Lamellibranchiata (31), Gasteropoda 
(42), Cephalopoda (32), together with some few Heteropoda and Pteropoda. 
Lower Ludlow and Aymestry Limestone. This group contains two or three species of 
Graptolites, a few Corals, Crinoids, Phyllopoda, and Trilobites, some species of Starfish 
(Asteroidea) belonging to five genera, and some Crustacea, belonging to the order Merosto- 
mata (Slimonia, Pterygotus), which, although represented in the preceding Llandovery and 
Wenlock groups, increases in numbers in the lower and upper Ludlow rocks. The species 
of Brachiopoda and Lamellibranchiata are far less in number than in the preceding Wenlock 
