BIOLOGICAL PAPERS I 47 



tinent. One of the oldest genera was Sparganophilns, in the 

 Jurassic, which seems to have remained behind in Xorth America, 

 while other American representatives went south, not much 

 before the Eocene, to Central and South America, where they 

 have ditterentiated widely and into numerous genera and species. 

 Sparganophilus species are known from ^Mexico, California, Flor- 

 ida. Illinois and the Great Lake region, and form a second group 

 of prominent endemic species. Probably the only reason why the 

 list of States is not longer is simply that no one has collected and 

 identified the worms from other States. It seems a little odd 

 that the genus Sparganophilus should have been founded by an 

 Englishman on specimens taken from the Thames, but there 

 seems excellent reason for believing that his conjecture was cor- 

 rect, viz. : that their occurrence there was accidental, due to the 

 introduction of a purely American form, perhaps with aquatic 

 vegetation. He was not able to find the species in later years, 

 and I think there is no record of any other occurrence of the 

 genus in the Old World. 



The third and last earthworm family to receive attention is 

 the Lumhricidae. These are the most recent forms to appear, 

 and seem to have been derived from tlie Glossoscolccidac, prob- 

 ably in Southwest Asia, where there is a great variety of endemic 

 forms. They probably invaded Europe in the Eocene and Xorth 

 America in the Oligocene. There are numerous endemic forms 

 in Europe and but few in the United States. These latter are 

 found chiefly in the Southeastern Atlantic coast region. Xone 

 are yet positively known to occur in Illinois. X'otwithstanding 

 the lack of endemic lumbricid species in Illinois, it is probable 

 that 90 to 95 per cent of all the specimens that would be taken 

 in random collections made in any of the settled districts of Illi- 

 nois or of the United States would be included in a few species 

 common also in Europe, and more than 50 per cent would belong 

 to a single species. Helodrilns caliginosa. These species are found 

 the world over where Europeans have settled and cultivated the 

 soil. They abound about the towns of Africa. South America 

 and Australia and crowd out the native species as they seem to 

 do here. 



The habits and mode of life of the earthworms are such that 

 they must necessarily be destroyed in any region subject to gen- 

 eral glacial action, and there can be no doubt that the earthworm 

 fauna of the glacial territories of Eurasia and X'orth America 

 have been occupied by invaders from the territory further south 



