146 It.LIXOIS ACADZMV Oy SvlEN'CE. 



ganophilits. These are the only papers that have dealt with new 

 species of earthworms based on Illinois material. A paper by 

 me in 1900, dealing chiefly w-ith other Oligochaeta, contained a 

 list of eleven species of earthworms known in the State. At pres- 

 ent my list includes three species and three varieties of Diplo- 

 cardia, of which two varieties are undescribed ; one species of 

 Sparganophilus, and seven species and one variety of Liimbrici- 

 dae, with three other forms not yet determined — a total of eight- 

 een different forms. 



It may be of interest to know- something of the source and gen- 

 eral relationships of the dift'erent types represented in the Illinois 

 fauna. At the present time there are more than one thousand 

 recognized species of earthworms in various parts of the world. 

 The great majority of these have been made known within the 

 last twenty years, chiefly through the efforts of five Europeans, 

 and one Swede, Eisen, who for a number of years lived in San 

 Francisco and worked on West and Central American species. 



These worms are grouped into four great families, of which 

 one is limited to Ceylon and southern India, and need not receive 

 attention. The other three are represented in Illinois. The great 

 family Mcgascolecidae includes more than half of the known 

 species, and is found chiefly in the tropical regions and the South- 

 ern Hemisphere. The most primitive type is the genus Eodrilus^ 

 which is represented by species in India, South America, Africa 

 and Australia, a distribution typical of the survivors of ancient 

 groups of other types of animal life. They date back at least as 

 far as the Triassic in the early Mesozoic. 



According to Michaelsen, a prominent investigator in this 

 field, Diplocardia was one of the first branches to develop from 

 the Eodrilus trunk, and probably appeared in Mexico or Central 

 America during the Jurassic in time for derivatives from it to 

 invade Africa by way of the land connection formerly existing 

 between Brazil and the African continent. Diplocardia itself 

 seems to have spread to the north instead of southward, and 

 species are known from Mexico, Lower California, Texas, Flor- 

 ida, Nebraska and Illinois. Its representatives are among the 

 dominant forms of our endemic species. 



The Geoscolecidae constitute another great family of the earth- 

 worm group, and seem to have developed at least as early as the 

 Jurassic in the northern continental area. Some went southward 

 through Europe into Africa, where many species now exist, while 

 a still greater development took place on the American con- 



