312 ANNELIDA 



D. riparia Smith. Length 25 cm.; diameter 3 mm.; color brown; 

 dorsal vessel single ; 2 pairs of spermathecae, in segment 8 and 9 : in wet 

 forest soil (Illinois). 



Family 9. GEOSCOLECIDAE. 



Aquatic or terrestrial, usually tropical oligochaets with 8 curved 

 setae in a segment, paired or not; clitellum concave ventrally; male 

 pores just before or in clitellum; gizzard in middle of oesophagus: 20 

 genera and about 90 species. 



Sparganophilxjs Benham. Prostomium not marked off from peri- 

 stomium; clitellum in segments 15 to 25; male pores on segment 19; 4 

 pairs of setae on a segment, a pair on each corner of the quadrangular 

 cross section : in the mud of streams ; 4 species. 



S. eiseni Smith. Length 20 cm.; diameter 2.6 mm.; dorsal setae 

 project laterally beyond the ventral; a pair of large glands open on seg- 

 ment 3; central and western states, in mud of springs. 



S. tamesis Benham. Length 10 cm. ; color red or blue; ventral setae 

 project laterally beyond the dorsal: Philadelphia; England; on water 

 plants. 



Family 10. LUMBRICIDAE. 



Earthworms. Terrestrial, occasionally aquatic, oligochaets with 4 

 pairs of setae to a segment; clitellum concave ventrally, not beginning 

 before segment 18 or after segment 61; male genital pores on segment 

 15 (rarely on segments 11 to 14) ; 2 pairs of testes in segments 10 and 11 

 (rarely 1 pair); 1 pair of ovaries in segment 13; cocoons egg-shaped: 

 5 genera and over 100 species. 



Key to the genera of Lumhricidae here described: 

 tti Peristomium completely divided dorsally by prostomium (Fig. 493). 



1. LUMBRICUS 



Ca Peristomium incompletely divided by prostomium (Fig. 494). 

 6i Gizzard occupies more than 1 segment ; clitellum reaches at least through 

 segment 32. 



Ci Clitellum begins mostly on segment 24 2. Eisenia 



Cz Clitellum begins mostly behind segment 24 3. Helodrilus 



62 Gizzard occupies but 1 segment ; clitellum reaches at most to segment 



27 4. ElSENIELLA 



1. LuMBRicus L. Peristomium (buccal segment) completely divided 

 by prostomium (Fig. 493); setae strictly paired; 3 pair vesiculae semi- 

 nales present in segments 10 and 11 which fuse together in the middle 

 line; 2 pairs of spermathecae, in segments 9 and 10; tail end flattened: 

 8 species, 3 American. 



