272 Professor Edward Forbes on the 



sent phenomena of striking interest and importance ; and as 

 they bear on the question of the possibility of a transmuta- 

 tion of species, we cannot do better than append a notice of 

 them to this account of the geology of Lycia. 



The fresh-water tertiaries of Cos are of considerable ex- 

 tent. They appear to belong to the same geological period 

 with those of the valleys of Xanthus and Cibyra. We have 

 seen that those Lycian fresh-water beds were of date poste- 

 rior to the miocene marine formations of the same region. 

 Thus we get an antedate ; and in Cos we get a distinct 

 afterdate, for there the same beds, or what were probably 

 beds of the same age, form the walls of a tertiary basin of 

 later date. This basin consists of a well-defined series of 

 marine deposits, containing numerous newer pliocene fossils, 

 identical with those of Rhodes and of Sicily. The Cos fresh- 

 water beds, and those of Lycia, may therefore be regarded 

 as older pliocene at latest. 



The fossils in the newer pliocene marine formation are ex- 

 tremely numerous, both as to species and individuals. They 

 consist of such testacea as now live in the neighbouring sea, 

 mingled with others extinct, or known only as inhabitants of 

 the Red Sea and Indian Ocean. Many species, too, now 

 very rare in the neighbouring seas, such as Nassa semistriata, 

 and Siliquaria anguina, are abundant in the fossil state, 

 whilst others now plentiful in the ^Egean are very scarce in 

 the tertiaries. Such shells as the Phorus and the Niso con- 

 spicuously represent the extinct forms. 



In the fresh- water strata, against which the marine newer 

 pliocene beds abut unconformably, as represented, A and B, 

 Plate III., there are also numerous and well-preserved fos- 

 sils ; shells of Paludina, Neritina, Melanopsis^ Melania, Val- 

 vata, Unio^ Cyclas, and Planorbis^ occur, marking the nature 

 of the deposit. With them, teeth of a Cyprmus were found ; 

 also leaves and stems of plants ; and in the uppermost stra- 

 tum shells of the common cockle. 



The great interest of this formation depends on certain ap- 

 pearances presented by the mollusca of the genera Paludina, 

 Melanopsis, and Neritma, found in great quantities in several 

 parts of it. They occur distributed in distinct horizons. 



