THE AMERICAN NATURALIST [Vol. XL 



Blood vessels of pharyngeal region well developed C. langi.. 



(Europe, X. America.) 

 Blood vessels of pharyngeal region absent or only slightly 



developed C. crystallinus. 



(Europe.) 



C''. Esophagus shorter than pharynx, indistinct. 



Ventral setje 8 to 12 in bundle, 1st postesophageal dilation 

 of intestine covered with anastomosing network of blood 



(Europe, N. America.) 

 Ventral setiE 6-7 in bundle, 1st postesophageal dilation of 



transverse blood vessels C. pellucidus. 



(X. America.) 



B'. Length of individuals 10-15 mm C.diaphanus. 



Chsetogaster langi Bretscher 



C. langi Bretscher, Rev. Suisse ZooL, vol. 3, p. 512, fig. 1, 1896; Micha( 

 len, Das Tierreich, Oligochaeta, Berlin, p. 21, 1900. 



ing specimens transparent. Prostomium blunt, indistinct. 



Setfe unequally bifid at distal end, 4 in a bundle. 

 Esophagus long. Ventral ganglia glandular in 

 form. Circulatory system with normal develop- 

 ment in the pharyngeal region, 1 pair of trans- 

 verse vessels (not developed as "hearts") in 

 esophageal segment. Length 1-2 mm. 



Between filaments of alga? in swampy places. 



One specimen (Fig. 3) referable to this species 

 was obtained early in July. There were several 

 minor characteristics not wholly in agreement with 

 Tl ji the description of C. langi, but in the absence of 



more material it must be placed here. 



Fig. 3. — chceU)- Chaetogaster pellucidus n. sp. 



scher(x2.5). For Transparent. Prostomiuni indistinct. Eves 

 see Fig'. '''"^ absent. Dorsal setu' absent, ventral sctic (i-7 

 in a bundle, biuncinate, with teeth une(|ual. 

 Esophagus short, postesophageal dilation (first stomach) sur- 



