42 LIAS OF ENGLAND AND WALES : 
i 
species, renders it impossible to give a list of the common and 
characteristic fossils that would apply to all localities. 
Some of the Ammonites are widely distributed (geographically) 
as A. planorbis (Fig. 12), A. Johnstoni, A. angulatus (Fig. 13), 
A. semicostatus, A. oxynotus (Fig. 16), A. armatus (Fig. 18), A. 
Henleyi (Fig. 24), A. capricornus (Fig. 26), &c. 
The most common fossils are Gryplma arcuata (incurvd) 
known as "Devil's toe-nails" (Fig. 35), Lima gigantca (Fig. 28), 
Ostrea liassica and Pentacrinus basaltiformis (Fig. 39) in the 
lower beds ; while Pleuromya costata, Inoccramus ventricosus and 
Belemnites (of many species) are abundant in the upper beds. 
Other species such as Cardinia Listeri (-tig. 30), C. ovalis, Hippo- 
podium ponderosum (called the horse's or ass's foot by the country 
people, Fig. 29,) and Montlivaltia Victoria are locally very abun- 
dant : but H. ponderosum occurs in the zone of A. angulatus in 
Yorkshire, much lower than it has been found elsewhere in 
England.* Lima pccthwides and Unicardium cardioidcs occur at 
various horizons, and so also do Rhynchonella calcicosta and 
R. variabilis (Fig. 37), but the latter species is referred to by 
Messrs. Tate and Blake as " a refuge for the uncertain forms 
obtained in the Lias." R. plicatissima seems to be the prevalent 
form in the lower beds in Yorkshire,! and both this species and 
R. calcicosta have been recorded by many geologists under the 
general name of R. variabilis. 
The great abundance of Ostrea liassica at the base of the 
Lower Lias, has given rise to the name Ostrea-beds, and it is 
sometimes accompanied by " Ostrea irregularis" which assumes 
various forms according to the organism to which it frequently 
attached itself. The prevalence of large forms of Lima gigantea 
in the higher beds of limestone, has led to the term " _zma-beds," 
generally synonymous with the zones of A. Bucklundi and A. 
angulatus. Again Spirifcrina Walcotti (Fig. 36) is locally abun- 
dant near Hadstock, and we have the term " Spirifer Bank ;" so 
also there are the Cardi?iia-beds and Uippopodium-beds of the 
western midland counties, which do not, like the Ostrea- and 
Lima-beds, mark very definite stratigraphical horizons. The 
Saurian beds, Insect and Crustacean beds, and Foraminifera zone 
may occur at different horizons, although locally applied to some 
particular bed, as will be noted in the sequel. Saurian remains 
are mainly found in the lower beds, comprising the limestones 
of the zones of Ammonites planorbis and A. Bucklandi. At 
Lyme Regis they are found mainly in the zone of A. Bucklandi, 
but also in some of the overlying clays ; at Street, Curry Rivell, 
Langport, and in parts of Gloucestershire, Warwickshire, and 
Leicestershire in the zone of A. planorbis; while in Yorkshire 
such remains are more abundant in the Upper Lias. 
Belemnites (" thunderbolts ") are rare in the limestones, indeed 
they are not known in the lower portion of the zone of Ammonites 
* We have the record only of Hippopodium (cast) from Lower Lias limestone at 
Queen Camel. 
f The Yorkshire Lias, p. 421. 
