LEE BARKER WALTON 3 5 



but in the absence of riiore material it must be placed 

 here. 



CH^TOGASTER PELLUCIDUS n. sp. 



Transparent. Prostomium indistinct. Eyes absent. 

 Dorsal set^e absent, ventral setae d-l in a bundle, biunci- 

 nate, with teeth unequal. Esophagus short, postesophageal 

 dilation first stomach) surrounded by 12 or more pairs of 

 non-anastomosing transverse blood vessels. Length 1.5 mm. 

 Number of segments in an individual from 9 to 11. Bud- 

 ding in all specimens observed. 



Sandusky Bay, Lake Erie. 



A considerable number of specimens of this small 

 Chastogaster were observed in cultures of aquatic plants 

 during July and August, and a number were stained and 

 mounted and are now in the collection of the Museum at 

 Kenyon College. All found were free living, while C. 

 limncei, to which it is most closely allied, normally occurs 

 on or in fresh-water snails. It is possible, however, that 

 they may have left their host as the age of the culture 

 increased. No snails were observed in the jar. 



Furthermore, Vejdovsky ('84) figures the first post- 

 esophageal dilation of C. limncei as being covered with an 

 anastomosing network of blood vessels, while in C. pelluci- 

 dus they are plainly non-anastomosing. 



Genus Dero Oken, 1815 



Prostomium rounded, eyes absent. Setae in four bundles 

 on a segment. Ventral setse uncinate, those of the seg- 

 ments 2 to 5 longer than the rest; dorsal bundle usually 

 beginning on the 6th rarely on the 5 th segment, composed 

 of a capilliform and one or two needle-like setae with 

 variously formed distal ends. Posterior end developed 

 into branchial filaments. Intestine with stomach. Blood 

 red. Nephridia paired from 6th segment. Testes in 5 th, 

 ovaries in 6th, spermathecas in 5 th segments. 



Fresh water. Europe, North America, Antilles, trop- 

 ical East Africa, Tonkin, Philippines; fifteen species. 



Four species of Dero have been reported from North 

 America: D. obtusa, D. limosa, D. vaga, and D. furcata. 



