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POPULAR SCIENCE REVIEW. 
Nor could the conditions of sea-bottom have had auytliino: to do with it, 
for its deposits show that the depth of the sea-bed must have varied much 
from time to time. The blue beds of the Maentwrog strata do not differ 
lithologically from the blue beds of the Menevian group. Hence he asks^ 
Might there not have been in these ancient epochs great oscillations of 
climate such as we have certain proofs of in more recent times ? Was it, 
he asks, the advent of a cold pluvia that drove southwards the Lower Cam- 
brian fauna, with the exception of a few modified forms fitted to thrive in 
a more vigorous climate ; and was it the return of a warm climate in the 
Tremadoc period that brought back the ancient types of life more or less 
changed ? Mr. Belt is notorious for his interesting and philosophical specu- 
lations, and this last is not less remarkable than many which have pre- 
ceded it. 
Fossil Corals of the TFest Indies. — In a paper read before the Geological 
Society of London (December 4), Dr. P. Martin Duncan concluded his 
series of memoirs on the above subject by giving a description of the Miocene 
corals from St. Croix, Trinidad, and by offering some supplementary obser- 
vations on the species described in the former papers. He also gave a com- 
plete and revised list of all the fossil corals he had described from the West 
Indies, including five species from the cretaceous strata ; four species and 
one variety from Eocene deposits ; and one hundred and two species and 
twenty-six varieties from the Miocene formation, making a total of one 
hundred and eleven species and twenty-seven varieties. Of the 'Miocene 
species eleven still exist, namely, six in the Caribbean Sea only, three common 
to that sea and the Pacific Ocean, and two in the Pacific Ocean and Red 
Sea, but not in the Caribbean. Twelve other species are common to Euro- 
pean deposits and the West Indian Miocene, ten being of the same age in 
both hemispheres, while two occur in the lower chalk in Europe. These 
twenty-three species being deducted from those of the West Indian Miocene, 
a large characteristic fauna still remains; and Dr. Duncan showed that the 
recent representatives of the characteristic genera composing it are for the 
most part inhabitants of the Pacific and Indian Ocean, the Red Sea, and 
the Australian waters, and that their tertiary congeners are found in Europe, 
Australia, Java, and Sinde. Of the fourteen genera thus enumerated, eight 
are not represented in the recent coral fauna of the Caribbean Sea. 
Volcanic Eruption in Nicaragua. — At the meeting of the French Academy, 
March 9, M. Ramon de la Sagra gave an account of the eruption of a volcano 
in Central America, which occurred in last December. The volcano was 
elevated in the middle of a plain, and continued to discharge lava for sixteen 
days. An enormous mass of mud and dust was thrown up, and formed a cone 
of seventy metres high, and covered an area of some miles. The fiames rose 
thirty metres above the cone, and were seen from an immense distance at sea. 
The Eruption of Vesuvius. — Eor a detailed account of the eruption of 
Vesuvius, which began on November 12, and is even j^et hardly over, we 
cannot do better than refer our readers to a long paper which appears in 
Elnstituty March 4, 1868. 
Earthquakes in the Cepholonian Islands. — M. Eouque has published a 
description of the earthquakes which occurred lately in these islands, and 
whose phenomena he himself experienced. He has noticed one interesting- 
