PALEONTOLOGY                                      M1»                                                 PALERMO

mais at each stage of the earth's history. For example, there have been times when faunas were essentially cosmopolitan, that is, when the same species were essentially worldwide in their distribution. There have been other times when the faunas were colonial, that is, when geographic diversity was very great. These facts and their explanation belong to paleontology. Paleontology also involves the study of the fossils in the earlier and later parts of a system. The second point mentioned above involves the determination of the question as to whether the fauna of a given system or part of a system originated from the fauna which lived in the same region at an earlier time; or whether it represents immigrants into the region where it occurs; or, lastly, whether it resulted from the commingling of resident forms with immigrants. The third point mentioned above is akin to the second. It considers a fauna in connection with its successors and descendants, instead of in connection with its predecessors and ancestors. A complete knowledge of paleontology would involve a complete knowledge of the living forms of each stage of the earth's history. It would do for all forms of life what history essays to do for the human race.

Paleontology is of great service in determining, or helping to determine, the age of rock formations, when their age could not be determined by other means. After the study of fossils has progressed so far as to make known the faunas of successive periods, the finding of the fossils of any one of these faunas in a given bed of rock determines the age of the bed. In making such determinations the general character of the fauna as a whole, rather than any single species, is to be relied on. Those phases of paleontology which involve the study of fossils for determining the age of formations or for determining the relations of land and water at successive periods or for the determination of geologic conditions of any sort are sometimes called paléontologie geology. Paléontologie geology, therefore, involves the study of fossils for the light they may throw on earth history. Paleontology also affords one of the chief lines of investigation for the solution of many of the problems of biological evolution. Those phases of paleontology which involve the study of fossils for the light they may throw on the history of the animal life of earth are paléontologie zoology. The term paléontologie botany would have a corresponding meaning in connection with plant life.

In a general way it is true that the animals and plants of any period are, on the whole, of higher types than those of preceding periods; but, while this is true as a general statement, it does not follow that the representatives of any class of animals in any given period are of higher type than

any of the representatives of the same class at an earlier time. For example, trilobites became extinct at the end of the paleozoic era. (See Geology.) The last of the trilobites were not higher in type than earlier representatives of the same group. The living representatives of some types of animals are less highly organized than ancient representatives of the same type. Paleontology seems to show that evolution is primarily differentiation, not ascent. Differentiation, in this connection, means the derivation of various types from a single type. Some of these derivative forms may be higher than the ancestral form, while others are lower. In the struggle for existence the higher types, on the whole, seem to have got the better of the lower, not to the extent of annihilating the latter, but to the extent of allowing the former to dominate them. While the succession of fossils supports, in a general way, the doctrine of evolution, it has, in few cases, afforded the specific forms which demonstrate a connected line of ancestry between living forms and very ancient ones.

It is probably true that many forms of life which have lived in the past were never fossilized. It is probably true that very many forms which have been fossilized have not been found. Most fossils which are now known are the fossils of species which lived in shallow water or in marshes and lakes. Relics of those forms of life which lived on dry land are rarely preserved. The relics of animals which live in the deep sea are likely to be preserved, but have rarely become accessible, for the fossiliferous formations of the land were, for the most part, made in shallow water. Present knowledge of ancient life is, therefore, very far from complete, and must always remain so.

R. D. Salisbury.

Palermo (pă-lër'mo), a seaport, archbishopric, former capital of Sicily, now the fifth city of Italy, stands on the northwest corner of the island in a valley before Mount Pel-legrino. The city was first known as the Phoenician Panormus. It was successively conquered by Pyrrhus (276 B. C), by the Romans (254 B. C), by the Vandals (440 A. D.), by Belisarius, the Saracens, the Pisans and the Normans. In the earthquakes of 1693, 1726 and 1823 the city suffered much. It revolted against the kings of Naples in 1820 and 1848, and was freed by Garibaldi in 18Ŏ0. The streets are lined with old and picturesque buildings of interesting architecture, the most conspicuous being the Cathedral of St. Rosalie, the royal palace, the churches of Martorana, St. John of the Hermits and San Cataldo, the archbishop's palace, town house and arsenal. A state university founded in 1805 has its seat at Palermo, with a teaching faculty of 61 and 1,083 attending students. The industries are insignificant, but the shipping