The geographical distribution of animals, with a study of the relations ...

chap, m.] CONDITIONS AFFECTING DISTRIBUTION. 39not only in depressions below the level of the sea but up to aheight of 900 feet above it. Borings for water made by theFrench government have shown, that these shells occur twentyfeet deep in the sand ;and the occurrence of abundance of salt,sometimes even forming considerable hills, isof the disappearance of a large body of salt water.an additional proofcockle is one of the most abundant of the shells found ;The commonand theEev. H. B. Tristram discovered a new fish, in a salt lake nearly300 miles inland, but which has since been found to inhabit theGulf of Guinea.Connected with this proof of recent elevationin the Sahara, we have most interesting indications of subsidencein the area of the Mediterranean, which were perhaps contemporaneous.Sicily and Malta are connected with Africa by asubmerged bank from 300 to 1,200 feet below the surface ;whilethe depth of the Mediterranean, both to the east and west, isenormous, in some parts more than 13,000 feet ; and anothersubmerged bank with a depth of 1,000 feet occurs at the straitsof Gibraltar. In caves in Sicily, remains of the living Africanelephant have been found by Baron Anca ;and in other caves Dr.Falconer discovered remains of the Elephas antiquus and of twospecies of Hippopotamus. In Malta, three species of elephanthave been discovered by Captain Spratt ;a large one closely alliedto E. antiquus and two smaller ones not exceeding five feet highwhen adult. These facts clearly indicate, that when NorthAfrica was separated by a broad arm of the sea from the rest oithe continent, it was probably connected with Europe ;and thisexplains why zoologists find themselves obliged to place it alongwith Europe in the same zoological region.Besides this change in the level of the Saharaand the Mediterraneanbasin, Europe has undergone many fluctuations in itsphysical geography in very recent times. In Wales, abundanceof sea-shells of living species have been found at an elevationof 1,300 feet; and in Sardinia there is proof of an elevationof 300 feet since the human epoch ; and these are only samplesof many such changes of level.But these changes, though veryimportant locally and as connected with geological problems,need not be further noticed here ; as they were not of a