No. 4-] NORTH-AMERICAN EARTHWORMS. 165 



Prostomium divides somite i by one-half. Dorsal pores, most 

 anterior one viii/ix (or x/xi). Spermidiical pores on xx. Sper- 

 niatJiecal pores on anterior Yi of somites ix, x, somewhat dorsal to 

 setae d. Prostate pores on xix, xxi. Oviducal pores interior to 

 setae a, no glandular ridge. Setae sigmoid, very faintly orna- 

 mented. Distance d-d vaoxo. than yi the periphery; ^-^ some- 

 what larger than a-b ; a-a three times, and b-b two and a half 

 times larger than a-b, no setae ab in xx. Penial setae curved, 

 not ornamented. Sperniathecal setae not differentiated. Clitel- 

 lurn saddle-shaped, xiii-xviii. Genital zone, a rectangular field 

 from posterior yz xviii-}^ xxii, extending laterally to center 

 between b-c. Two deep grooves from yi xix-% xxi, the con- 

 vexity of which is outwards, except in the center of xx, where 

 it is turned towards median line ; one median papilla on xxii ; 

 one pair papillae on xix in line with setae b ; one pair papillae 

 on xix and xxi, interior to grooves ; one pair papillae exterior 

 to grooves on each of xix, xxi, xxii (two pairs papillae on each 

 of xix, xxi, and three papillae on xxii). Septa, thickened are : 



vi/vii,'vii/viii, viii/ix, ix/x, x/xi, xi/xii. 



Oesophagus, no calciferous folds or thickenings. Gizzards in v, 

 vi. Sacculated intestine commences in xvi. Dorsal vessel single. 

 Hearts, three pairs in x, xi, xii. NepJiridia, meganephridia, com- 

 mence in ii, pores intersegmental in front of setae d. Testes, 

 X, xi. Spei'in funnels, x, xi. Sperm ducts open in central part 

 of groove in xx. Sperm sacs, one pair pre-septal in ix, one pair 

 post-septal in xii. Oviducts open in front of and interior to 

 setae a. Prostates very thin, even, bent in four folds, confined 

 to one somite each. SpermatJiecac, two pairs in viii, ix, retort- 

 like, with a small, short-stalked, ear-like diverticulum below the 

 center. No specialized spermathecal setae. 



Habitat. — Omaha, Nebraska. (See note on page 172.) 



DiPLOCARDIA ElSENI (MiCHAELSEN). 



Definition. — Color, dorsally gray or pigmented, clitellum 

 violet gray. Size, 150 mm. by 2 mm. Somites, 165; viii-xiii, 

 smoother and wider than the others. Prostomium divides somite 



