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Show 1895.] MB. F. E. BEDDAED ON NEW EAETHWOBMS. 227 regions of South America. Michaelsen does not pretend to definitely assign this species to the genus Cryptodrilus; he only placed it there (with a query) pending the revision of the Cryptodrilidae. The classification of that family is one of the most difficult tasks for the systematist; the differences are so slight between species and species that the boundaries of genera are extremely hard to draw. I believe, however, that it is possible to define the genus Microscolex by the following characters :- (1) Nephridia paired, beginning in the second to fourth segment. (2) Male pores upon segment xvii. (3) Sphermiducal glands tubular, provided generally with penial setae. This definition is naturally somewhat wider than that adopted by Eosa, the founder of the genus. But a number of n e w forms which I shall describe immediately necessitate an expansion of the genus. They do not present a sufficient number of salient differences to warrant the formation of a new genus. I have already proposed to include m y genus Rhododrilus in Microscolex, and I do not see sufficient reasons for retaining the genus Deltania of Eisen. Cryptodrilus spatulifer of Michaelsen must, I think, especially in view of the new species to be described here, be relegated to Microscolex. The size is really the only bar to its inclusion. I find a good many individuals of Microscolex dubius which are really quite as large as many individuals of Microscolex spatulifer. The distribution of this genus is interesting. It is the commonest earthworm in point of number, and nearly so in point of species, in the temperate parts of South America. I quite agree with Eosa that it has probably been introduced into Italy and possibly also into Australia; I described a species from Teneriffe and one from Algeria which are very likely to be regarded in the same way. The remaining species occur in N e w Zealand (Microscolex minutus and M. novce-zealandice) and in California (the genus Deltania of Eisen). Dr. Michaelsen's collection contained examples of the following species : - 1. Microscolex spatulifer (Mich.). 2. Microscolex dubius (Fletcher). 3. Microscolex griseus, n. sp. 4. Microscolex michaelseni, n. sp. 5. Microscolex corralensis, n. sp. 6. Microscolex diversicolor, n. sp. 7. Microscolex longiseta, n. sp. 8. Microscolex robustus, n. sp. 9. Microscolex modestus, Rosa. 10. Microscolex gracilis, n. sp. 11. Microscolex papillosus, n. sp. It will be seen, therefore, that this collection contains a large number of new species; evidently South America is the headquarters of this genus as it is of Acanthodrilus. 15* |