180 PROCEEDINGS OF THE NATIONAL MUSEUM vol.84 



9 are somewhat larger, but otherwise they are similar. The ducts are 

 short with thick muscular walls and one or two short diverticula 

 containing chambers having folds in the inner layer and a lumen 

 opening into the duct. The ampullae are large and with rather thin 

 walls. 



PLUTELLUS OREGONENSIS SWIFTAE, new subspecies 



Distinguishing characters. — Length of preserved specimens, not 

 strongly contracted, 60-77 nnn. Diameter, 2.5-3.5 mm. Number of 

 somites, 116 in each of two specimens. Setae are widely paired ; an- 

 terior to the clitellum approximately aa: ah:hc\ cd=^:l'.Z:2>\ del 

 about one-third of circumference. Penial setae similar to those of 

 the typical form in dimensions, form, and location. Transversely 

 elongate 2:)apillae on 7/8, 8/9, and 9/10 and extending laterally to 

 seta lines a. Normally, apparently one pair of papillae on 19/20. 

 (Asymmetrical in type specimen.) In 15 and 16 a calciferous gland 

 enlargement is present ; numerous wide folds extending nearly to the 

 middle of the lumen, but less highly developed than in the typical 

 form. Nephridia, circulatory, and reproductive organs similar to 

 those of the typical form. 



Material. — The description is based on two specimens collected by 

 F. M. McElfresh in April 1901 in the bottomlands of Marys Kiver 

 in the Cascade Mountains and sent by him to the writer. Only one 

 of the specimens, the holotype (U.S.N.M. No. 20248), was sexually 

 mature, and the anterior 24 somites of this were divided in the 

 median sagittal plane and sagittal sections were made from one half 

 and transverse sections from the other half. This form is similar 

 to P. oregonensis in so many respects that it seems desirable to treat 

 them as subspecies of the same species, and the selection of the other 

 one as the typical form is due chiefly to the fact that a greater num- 

 ber of specimens of that form were available for study. The more 

 important differences noticed are in the number and location of the 

 genital papillae. 



The two specimens were less contracted than those of the typical 

 form, probably as a result of different methods of preservation. 

 Length of tj^pe, 77 mm; diameter, 3-3.5 mm. Other specimen, 60 

 by 2.5-3 mm. Each specimen has 116 somites. Triannulate somites 

 begin at the eighth. The clitellum on 13-18 is complete on 14-16, 

 with the ventral part about one-third as thick as on the dorsal side. 

 Ventral median papillae are present on 7/8, 8/9, and 9/10 and extend 

 laterally to seta lines a. Paired papillae posterior to the clitellum 

 are asymmetrical in the specimen studied, being at 19/20 on the left 

 side and at 20/21 on the right side. Anterior to the clitellum ap- 

 proximately ««: «&: &<?:C6?=5: 2: 4: 4 and posterior to the clitellum 

 aa:ab:l)c: (?f/=4 : 1 : 3 : 3 : dd is, about one-third of the circumference. 



