1896. NOTES AND COMMENTS. 299 



six species of Acanthodrilus and something like the same number of 

 Microscolex exist outside of this area. The iceberg theory of migration 

 might be called in, perhaps, to explain the phenomena ; but it offers 

 great difficulties. It may be granted that the cocoons might be 

 detached with a quantity of the earth in which they are usually 

 deposited and find their way on to a glacier, and so, with its broken 

 end, float out to sea. Plenty of dangers are run during these pre- 

 liminary steps, but the real dangers only begin when the berg is well 

 out to sea, and, while gradually diminishing in size, is exposed to the: 

 splashing of the waves of that stormy ocean. This would be almost 

 certain to destroy some of the embryos contained within the cocoons. 

 If these perils are escaped it can be but seldom ; such rare occurrences 

 would surely hardly account for the close similarity of the earthworm 

 faunas that has been referred to. If the extension of the land be 

 denied, some explanation is much wanted for these facts. 



Distribution of Earthworms. 



The California Academy of Sciences is to be congratulated, not 

 only on the excellence of its publications in the matter of type and 

 lithography, but on the good work done by its contributors. One of 

 the latest numbers of the quarto memoirs of this Academy is before 

 us, and deals with a large series of new species of earthworms from 

 California, by Dr. Gustav Eisen. It is the second part of his 

 " Pacific Coast Oligochaeta." For some years past Dr. Eisen has 

 been engaged in the study of the American Oligochaeta, both fresh- 

 water and terrestrial, of which there is a greater variety than in 

 Europe. In this latest publication, Dr. Eisen has described five or 

 six species of the Acanthodrilidae, Benhamia and Acanthodrilus, and four 

 new species of Sparganophilus. This latter genus was originally found 

 in the Thames by Dr. Benham, but the occurrence of so many 

 distinct forms in the North American continent seems to point to that 

 area as its proper habitat. One species of the genus, of which, 

 unfortunately, no other details are at present forthcoming, was found 

 to possess eyes, at present a unique example among the earthworms. 

 Eyes, as is known, occur in certain Naidae, but no trace of them has as 

 yet been met with in any terrestrial worm. Sparganophilus, however, 

 though belonging to a family, Geoscolicidae, which is chiefly terrestrial 

 in habit, is itself aquatic, as are indeed a few other genera of the 

 same family. The distribution of Benhamia is the most puzzling fact 

 in the distribution of the entire order. Dr. Eisen, unfortunately, adds 

 to the difficulties by describing what appear to be unquestionably indi- 

 genous forms from California. It is a genus which is eminently 

 tropical in range, though a few (? imported) species have been found 

 in extra-tropical regions, e.g., in Germany. Dr. Michaelsen regards 

 tropical Africa as its home, and in that continent are undoubtedly the 

 largest number of species of the genus, which is always met with in 



