212 Miscellaneous. 



reservoirs were carried to a certain height by upheavals, which 

 lowered the temperature of their surface. lu the course of these 

 events the marine fauna disappeared, with the exception of a fcAV 

 fishes and Crustacea less sensitive than their fellows to the action of 

 fi'esh water. 



Prof. Heller has carefully investigated the marine forms inhabit- 

 ing the Italian lakes. He confirms and extends most of the disco- 

 veries of M. von Martens, at the same time rectifying some of them. 

 He shows that Palwmon lacustris is a species very widely diffused 

 in the fresh waters of the Mediterranean basin. Ho cites it in the 

 lake of Albano, in the ditches of the terra jirma in the neighbour- 

 hood of Venice, in the marshes round Pavia, in the lake Trasimene, 

 in that of Garda, in the brooks of Dalmatia, in Corfu, in the lake of 

 Albufera in Spain, and, finally, in Egypt. But this 8i)ecies is not 

 peculiar to the fresh Avaters ; it still exists in the North Sea and the 

 Baltic. M. Heller, in fact, recognizes in it the species introduced 

 into science under the names of P. varians and P. antennanus. It 

 appears, however, to be wantiag in the Mediterranean. M. Milne- 

 Edwards certainly mentions it, in his ' Histoire NatureUe des Crus- 

 taces,' as occurring in the Adriatic ; but the author himself has 

 found this statement to be erroneous, the specimen in the Paris 

 Museum having rcaUy been derived from Lake Trasimene. The 

 crustacean in question is distiagiiishcd from all the Palannons by 

 the want of a palpus on the mandibles, by which it approaches the 

 genus Anchhtia. But as other characters distinguish it from that 

 genus, M. HeUcr proposes for it the new generic name of Palamo- 

 netes (P. varians). It is probable that this PaJa^monetes existed at 

 a prehistoric period m tlie Adriatic and Mediterranean, as at jire- 

 sent in the bays of the !N'orth Sea, in places where the water was 

 comparatively not very salt. Subseijuently, after the transformation 

 of the bays into lakes, the species gradually accommodated itself to 

 the fresh Avater, although wdthont attaining its original size. In 

 fact the freshwater individuals arc always smaller than the marine. 

 A similar lot may be reserved in the future for another crustacean 

 of the Adriatic. Neplirops norver/iciis, which is so common in the 

 northern sens, occurs here and there in the Mediterranean and the 

 Adriatic. In the Gulf of Quarnero, however, it exists in considera- 

 ble quantity. If this gulf should one day be converted into a lake 

 by an upheaval, this animal would, no doubt, in time become a true 

 freshwater crustacean, whilst its congeners would still live in the 

 northern seas. 



Thelpliusa jluviatilis is not entirely confined to the lakes of Albano 

 and Nemi ; it occurs also in the south of Italy, in Greece, in Cyprus, 

 ill the Crimea, in Syria, and in Egypt. As regards the !:<pha'roma 

 of the Pontine Marshes, it presents the greatest resemblance to a 

 species {S. gramdatum) inhabiting the Adriatic and Mediterranean, 

 althoiigh they cannot be completely identified. 



Lastly, M. Heller describes two new freshwater Crustacea of ma- 

 rine forms. The first is an Amphipod {Gammarus Veneris) found 

 by M. Ivotschy in the Well of Ycnus, near Hierokipos, in Cyprus, at 



