1844.] 379 



the trachyte being stratified like that found near Smyrna. The 

 tertiary hills on the margin of the Scio channel, near the town of 

 Tchesmeh, and in the island of Scio opposite to it, seem also to be 

 of fresh-water origin, as they closely resemble those of the Gulf of 

 Smyrna. 



The facts made out from these investigations tend to prove the 

 former existence of a large lake in the eastern part of the Archi- 

 pelago, where the sea now attains a very considerable depth*, 

 and that subsequently a succession of volcanic eruptions on a 

 grand scale took place over the bed of the lake. A long period of 

 tranquillity must, however, have preceded these eruptions, during 

 which 500 or 600 feet of a vertical series of beds had been depo- 

 sited throughout the lake. By this sudden outburst of igneous 

 matter, parts of the deposit were raised into hiUs of considerable 

 elevation, whilst the accumulations of the heated and melted fluids 

 poured over the bottom, formed mountains and high ridges of con- 

 siderable extent round each focus of eruption. In the tertiary hills 

 there is evidence of a denuding power at elevations above the 

 present sea level. 



Having carried this ancient lake into the depths of the Archi- 

 pelago, the question then arises as to its former boundary, a ques- 

 tion which extended observations only can determine. 



2. Note on the Fossils collected by Lieut. Speatt in the Fresh- 

 water Tertiary Formation of the Gulf of Smykna. By Pro- 

 fessor Edwakd Forbes, F. L. S. 



Lieutenant Speatt has found eleven species of fresh- water shells 

 (aU univalves) and a cast, apparently of a Helix, in the fresh-water 

 limestone of Vourla. 



Of these, two belong to the genus Limneus, one of which agrees 

 with the Limneus longiscatus of the Paris basin and the Isle of 

 Wight fresh-water bed, and the other is apparently the Limneus 

 ventricosus of Brongniart ; also a Paris basin shell- 

 Five species belong to the genus Planorbis. One of these 

 is Planorhis rotundatus, a well-known eocene fresh-water fossil. 

 Three are closely allied to, if not identical with, Paris basin fossils, 

 and one is new. 



Two belong to the genus Paludina. One of these appears to be 

 the Paludina atomus of the Paris basin. The other is new. 



One belongs to the genus Melanopsis. It is the Melanopsis 

 buccinoidea, a species which, commencing its range in the oldest 

 tertiary strata, has lived on to the present day, and is now a 

 common inhabitant of western Asia, northern Africa, and the 

 southern parts of Europe. 



* At about five miles off the north extremity of Karabournou the depth is 

 100 fathoms, and continues to increase beyond. 



