The Middle and Upper Devonian rocks of the Torquay Promontory give evidence of a volcanic phase in Middle Devonian times, recurring in the Upper Devonian, and completed by a hypabyssal phase, which was post-Culm and pre-Permian. The tuffs are basic in nature, of glass and lava fragments, cemented by calcite. The only lava recognized is a spilite, probably Upper Devonian.

Complementary rocks: a soda-porphyrite and an augite-lamp-rophyre, have been recognized at Babbacombe.

An albite-dolerite is described from Black Head, carrying small amounts of olivine and with the characteristic albite-segregation veins. This mass has been shown to include the Ilsham Manor and the Red Rocks outcrop at Babbacombe. Metasomatic change due to silicification is characteristic of its flanks: this is especially developed at Anstey's Cove, where quartz-hæmatite veins are later than the cleavage of the slates.

It has been shown that there is strong evidence for the post Culm date of this intrusion and hence for the tectonic movements of the area. The latter have been in the sequence:—tilting, intrusion, folding, thrusting, cleavage, and faulting, Some strike faults may be anterior to all these, but were repeated after the cleavage movements.

Roade cutting was considered to be one of the great works in the construction of the original London and Birmingham Railway (afterwards the London and North-Western Railway) between 1833 and 1838, being about 1½ mile in length, of considerable average depth, a good part of which consisted of hard rock—the Great Oolite Limestone.

This small, though extremely interesting area of Carboniferous Limestone is situated about 4 miles north-east of Bridgwater and ¾ mile north-east of the village of Cannington.

For several reasons it has attracted a large number of workers. Fossils are scarce (at first the mass was thought to be unfossiliferous), and hence for a long time the “Devonian or Carboniferous” question of age was a bone of contention. Also, the final acceptance of its Avonian age showed that productive Coal Measures were probably deposited in the area between the Mendips and the Quantock Hills.

It is now generally accepted that there is no essential difference between igneous intrusion and the deposition of the minerals which fill the deep veins. Both igneous rocks and deep veins were formed from magmatic material, their differences being due to successive differentiation and not to difference in origin.

Although much work has been done in connexion with fossil Ostracoda, little attempt seems to have been made to correlate the results arrived at, and, in consequence, much of the value of the work of such writers as Rupert Jones, R. S. Bassler, E. 0. Ulrich, etc., is in danger of being overlooked. The following is an attempt to collect together in an orderly manner the work of these and other writers, and at the conclusion it will be indicated by reference to the classification of the Purbeck Beds in the Vale of Aylesbury, the use which may be made of these minute fossils to settle questions of great geological importance in cases where no other evidence is forthcoming.