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NEW NORTH AMERICAN EARTHWORMS 167 



External characters. — The color of the living specimen was a pale 

 flesh tint, more pronounced on the 10 anterior somites. The clitellum 

 was fleshy orange in color. The length when fully relaxed was about 

 300 mm, but the preserved specimen has a length of 155 mm. Diame- 

 ter, 7-8 mm. Number of somites, 282. Prostomium small and ap- 

 parently prolobic. The setae are relatively small and widely spaced; 

 approximately aa : ah : he : cc?=6 : 2:3:3. In the posterior region dd 

 is but little more than one-half of the circumference, while in the 

 anterior region it is nearer two-thirds of the circumference. The 

 length of the setae is variable and commonly 0.4-0.5 mm, with a 

 maximum diameter of about 0.028 mm. The penial seta of the sec- 

 tioned part is seta h of 18, and seta a is lacking. There is a partially 

 developed reserve seta in each of the setal sacs a and h. The length 

 of the fully developed penial setae is probably not more than 1 mm. 

 The maximum diameter is less than 0.04 mm. They are nearly 

 straight throughout the greater part of the length, but the distal part 

 of the protruded portion is rather abruptly curved and tapers. The 

 distal end has very minute sculpturing, difficult to recognize. The 

 male pores and the setal apertures of a and h are very close together. 



The clitellum is incomplete ventrally and includes 13-21. The 

 thickened glandular wall terminates ventrally between seta lines h 

 and c. Paired ventral papillae are present on 14/15-16/17 and 19/20 

 in line with the ventral pairs of setae, and small asymmetrically 

 placed ones are present on 20/21 and 21/22. Dorsal pores are pres- 

 ent, posterior to the clitellum. Nephridiopores are very inconspicu- 

 ous and situated near the anterior margins of the somites. The male 

 pores are paired on 18 slightly laterad of seta line h. Oviducal pores 

 are paired on the anterior part of 14 nearer to seta line a than to 

 the median ventral line and are borne on an elongate transverse 

 elevation. Spermathecal pores are paired on 7/8 and 8/9 in seta 

 line h. 



Internal characters. — Septa 7/8-10/11 are strongly thickened and 

 6/7 and 11/12 less strongly thickened. The alimentary tract in- 

 cludes an eversible buccal sac followed by a pharynx with a thick 

 muscular dorsal wall and a gizzard in 5, which is enlarged and 

 forces the septa of 5/6 and 6/7 posteriad. The calciferous gland 

 region in 10-15 is of the simpler type similar to that found in M, 

 ainericanus. There is a gradual increase in diameter and in the 

 number and length of the diverticula from 10 to 13, with maximum 

 development in 14 and 15, where some of them extend nearly two- 

 thirds of the way to the middle of the lumen. In 16 and 17 the lin- 

 ing layer of the esophagus forms longitudinal folds not extending 

 far into the lumen. The enlarged intestinal tract begins at about the 

 20th somite and has a definite typhlosole. The circulatory system 

 has not been carefully studied, but there are smaller hearts paired 



