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Show 1895.] MR. F. E. BEDDARD ON NEW EARTHWORMS. 211 The number of individuals is much greater; but the proportion of new species is not so great. The actual number of new species is, however, much greater. Considering that a good many papers have been written upon the terrestrial Oligochaeta of this part of the world by Michaelsen, Eosa, and by myself, I was unprepared for the very large number of new species which Dr. Michaelsen has got together and kindly entrusted to me for description. The collection consisted exclusively of members of the four following families : Lumbricidaa, Perichaetidae, Acauthodrilidae, and Cryptodrilidae. The total absence of Eudrilidae is not of course remarkable, except perhaps as regards the genus Eudrilus itself. The entire want of Geoscolicidae is much more singular. Hitherto, however, the only Geoscolicid which has been found south of the Eio Grande do Sul is the Titanus forguesi of Perrier. North of this point the family is apparently one of the most abundant. The Perichsetidae are represented only by a single individual, but this family is not one which is common anywhere in the South-American continent. Their headquarters, as regards the N e w World, are certain of the West-Indian Islands. Lumbricidae are fairly abundant in Dr. Michaelsen's collection; but then this cosmopolitan family is abundant everywhere. I am convinced that here as elsewhere the Lumbricidae have been introduced. Dr. Michaelsen informs me in a letter that he observed the proportion of Lumbricidae in his gatheriugs to diminish with the increased distance from the coast; in cultivated gardens near to the seaboard this family was the most abundant. This fact (which Prof. Spencer has confirmed for Australia) is an argument for regarding these worms as the result of intercourse between Europe and the countries in question. A fact which obviously points in the same direction is the invariable identity of the exotic species with European or North-American forms. The characteristic indigenous forms of the temperate regions of South America are of the families Acanthodrilidae and Cryptodrilidae. Both of these families occur in Central and North America as well; but they are not by any means relatively so abundant in the south temperate region of the continent. Moreover, the genus Acanthodrilus (s. s.) is only found in this part of the world, being represented in the tropical aud north temperate parts by Benhamia, Trigaster, and Diplocardia. A n examination of this collection, in fact, seems to confirm what previous researches upon the earthworm fauna of America appeared to indicate-namely, that it is possible to divide the Neotropical region into a tropical and a temperate section. The former is characterized by Geoscoli-cidas, the latter by the genus Acanthodrilus. But in this last genus we have a correspondence between temperate South America and New Zealand. This correspondence is also emphasized by the great prevalence of Microscolex in South America and its fairly common occurrence in N e w Zealand. The Cryptodrilidae collected by Dr. Michaelsen belong exclusively to this genus ; and they are quite as abundant, though perhaps there are not so many species as the Acanthodrilidae. Microscolex, however, is not so restricted to 14* |
