172 PROCEEDI]SrGS OF THE NATIONAL MUSEUM vol.84 



Material. — Six specimens were collected at ISIiiltnomah, Oreg., in 

 FebruaiT 1931. The specimen selected as the holotype (U.S.N.M. 

 no. 20246) was split in the median sagittal plane of somites 1-21, 

 and one-half was removed and cut into transverse sections, which are 

 the source of most of the data concerning the internal anatom3\ 



External characters. — The length of the type specimen is 131 mm; 

 the maximum diameter is 7 mm, and the average diameter is approxi- 

 mately 5 mm. The average length of the six specimens is 135 mm, 

 with extremes of 115 and 170 mm. The average of the maximum 

 diameters of the six specimens is about 6.6 mm, and of the average 

 diameters about 4.5 mm. The diameter near the middle of the 

 clitellar regions is somewhat less than that in adjacent regions of 

 the preserved specimens. The number of somites is 202 in the type, 

 and the average number in the six specimens is 198, with extremes of 

 191 and 205. 



The setae are relatively small in the anterior region, usually not 

 over 0.35 mm in length and with a maximum diameter of 0.028 mm. 

 They are minutely sculptured on the distal part. Most of the an- 

 terior somites have their full quota of eight setae to the somite. In 

 the anterior region the spacing is approximately aa'.db:})c'.cd— 

 20 : 3 : 12 : 5, with del about three-fifths of the circumference. Pos- 

 teriorly it is more nearly aa : ah : be : ed— 12 : 3 : 9 : 5, with dd but 

 slightly more than one-half of the circumference. The penial setae 

 are long and slender, with a nearly uniform rate of curvature but 

 somewhat increased in the distal region. The curvature is in a plane 

 transverse to the longitudinal axis of the worm, with the convex 

 side mesad. Only a small part of the length is protruded, and this is 

 curved laterad. The distal part is finel}^ sculptured, and the end is 

 relatively blunt. The length is about 1.8 mm, and the diameter is 

 0.045 mm throughout most of the length. With each penial seta 

 of the type specimen there are closely associated reserve setae, of 

 which one is about full size and others are only partially grown. 



The prostomium is small and prolobic. The anterior six somites 

 are biannulate or partially triannulate and the others definitely 

 triannulate. The clitellum includes 13-19 and invades 20 in two 

 specimens. It is incomplete ventrally and in some specimens seems 

 slightly tan-colored. Median ventral papillae are present on 9/10 

 on each of two specimens, on 9/10 and 10/11 on each of two other 

 specimens including the type, and only on 10/11 on another one. 

 The ijapilla on 10/11 is the larger. Paired ventral papillae on 16/17 

 are present in each of the six specimens, and one of them has an 

 additional papilla on the left side of 15/16. On each of most of the 

 specimens there are paired ventral papillae, transversely elongate, 

 on 19/20-22/23, while on the type specimen they are on 19/20-21/22. 



