NEW NORTH AMERICAN EARTHWORMS 177 



is an increase in diameter, the number of folds is about doubled, the 

 folds are much thinner and extend nearly to the middle of the 

 lumen. This type of structure is continued in following somites 

 to the middle of the fifteenth and is similar to that of the simpler 

 type of calciferous glands in some species of Diplocardia and 

 Megascolides. Posterior to 15 there is a marked decrease in the 

 number and height of the folds of the lining epithelium and in the 

 diameter of the esophagus. The enlarged intestinal region begins 

 in 18 and a typhlosole is present. 



Nephridia are paired in the second and following somites. Dor- 

 sal and ventral blood vessels are present; subneural and lateroneural 

 vessels are lacking. Short, longitudinal vessels connected with the 

 blood plexus of the median dorsal wall of the esophagus in 8-13 

 seem to be representative of a supra-esophageal vessel. Short lon- 

 gitudinal vessels on each side of the median ventral part of the 

 esophagus in 8-13 seem to represent a pair of subesophageal or 

 laterolongitudinal vessels. Paired dorsal hearts are present in 7-9, 

 and paired dorso-esophageal hearts are present in 10-12. No trace 

 of hearts was found in the thirteenth somite of either of the sec- 

 tioned specimens. 



Spermaries and spermiducal funnels are paired in 10 and 11, 

 and the sperm ducts of either side unite in 13 and form a single duct, 

 which unites with the prostate gland in 18. The exact place of 

 union with the gland could not be determined in either series of 

 sections. Paired sperm sacs in 11 and 12 communicate with 10 and 

 11, respectively, near the esophagus. A pair of prostate glands is 

 present in 18. The glandular part is long and contorted and of the 

 tubular type. The muscular duct of each is shorter, of smaller di- 

 ameter, and also contorted. Ovaries and oviducal funnels are paired 

 in 13 and oviducts in 14. No ovisacs were found. Paired sper- 

 mathecae are present in 8 and 9, those of 9 being largest. The ampul- 

 lae have moderatelj'^ thin walls, and the lining layer has numerous 

 low ridges. The ducts are short and have thick walls, and the 

 lining layer forms several ridges. A short diverticulum with one 

 chamber having a ridged lining is developed on the anterior wall of 

 each of the ducts in 8, and in a similar position a short diverticulum 

 with three or four chambers is formed on the wall of each of the 

 ducts in the ninth somite. 



PLUTELLUS OREGONENSIS. new species 



Distinguishing characters. — Length of strongly contracted speci- 

 mens, approximately 50 mm. Diameter, about 4 mm. Average 

 number of somites in five specimens is 117. Setae are widely paired, 

 with spacing in anterior region approximately aa'.ab'.hc'. cd= 



