1 48 Geological Society. 



and are not necessarily accompanied by violence. 13. That the 

 reticulation of such crevices does not disprove their being contem- 

 poraneous. 14. That caves may be produced in strata by the un- 

 dermining action of the sea. 15. That limestone may be conso- 

 lidated without the application of either heat or pressure. 



The Bermuda Islands furnish a striking example of the intermix- 

 ture of land and sea shells with the bones of birds and tortoises, 

 and likewise with vegetable remains. Some of the specimens which 

 accompany the paper have a structure distinctly oolitic, and in some 

 I observe the delicate red tint which is met with in the chalk beds 

 of Yorkshire, or the oolite of Dijon. The cause of this, and still 

 more, the origin of the sand, the detritus of rubies which occurs in 

 one part of the shore, are curious subjects of inquiry. It is also 

 remarkable that breccias should be found at Bermuda, similar to 

 those of Nice, the island of Cerigo, and Gibraltar. 



A paper on the arrangement of Fossil Fishes, read at the first 

 meeting after the recess, and ably commented upon by its author, 

 M. Agassiz, received from you more than usual marks of approba- 

 tion. M. Agassiz informed us, that as yet he had not found any 

 species identical with those of our present seas, with the exception 

 of one small fish which has been discovered in Greenland imbedded 

 in geodes of clay, the geological age of which is undetermined. In 

 the newer tertiary formations, viz. the Crag and superior Apennine 

 beds, the species for the most part exhibit a relation to the genera 

 which dwell within the tropics, but in the older tertiary, viz. the 

 London clay, the marine limestone of Paris and the rock of Monte 

 Bolca, at least a third of the fishes belong to genera that are ex- 

 tinct. In the Chalk more than two thirds belong to extinct genera, 

 and if the grouping of strata were regulated only by ichthyological 

 considerations, this rock would be more properly classed with the 

 tertiary formations than the secondary. Below the Chalk not one re- 

 cent species has been met with ; in the Wealden Beds, the Oolitic 

 Beds, and the Lias, even the genera are all different from those in the 

 chalk. Below the lias, two out of the four orders, under which 

 M. Agassiz comprehends all the fishes that are known, viz. the Cyclo- 

 idean and the Ctenoidean, entirely vanish, while the other two orders, 

 rare in our days, suddenly appear in great numbers, together with 

 large sauroid and carnivorous fishes. Of the fishes that occupy the 

 Transition Rocks few have been brought to light, and no peculiar cha- 

 racter has yet been affixed to them. In general the more ancient 

 fishes are the best protected by scales. Those which fire more an- 

 cient than the green-sand exhibit none of those marks by which we 

 can determine in the fishes of our own times whether the water in 

 which they live be fresh or salt j the species always changes with the 

 formation, and frequently, as we see, the genus also. It would ap- 

 pear, therefore, that greater changes take place in the higher order 

 of animals than the lower in equal periods of time. 



Your award of the Wollaston medal to this eminent naturalist 

 has led to the most advantageous results. By that award M. Agassiz 

 having been induced to come over to this country, has received in all 



