THE AMERICAN NATURALIST 



[Vol. XL 



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

 dilation of C. Umncri as being covered with an anastomosing net- 

 work of blood vessels, while in C. pellucidus they are plainly non- 

 anastomosing. 



Genus Dero Oken, 1S15 



Prostomiuni n.iitidcd. eyes absent. Seta- in four bundles on 



longer than the ivM ; dorsal bundle usuallv beginning on the Gth 

 rarelv on the :)ili .eginei.t, coinix.sed of a (•aj)illifnrm and one or 

 t^^<. iieedle-like M-ta- ^^\\\^ vari.>,i.K formed di.tal ends. IWerior 



Blocxl red.' Xephridia paired from (ith segment. Testes in .)th, 

 ovaries in (ith, spermatheca' in oth segments. 



Fresh water. Europe, North America, Antilles, tropical Fast 

 Africa, Tonkin, Fhilippines; fifteen sj)ecies. 



Four species of Dero have been reported from North America: 

 D. obtusa, D. limosa, D. vaga, and D. furcaia. 



Dero vaga (Leidy) 



Aulophmus vagus Leidy, Amer. Nat., vol. 14, p. 423, figs. 3, 4, 1880; 

 Reighard, Froc. Amer. Arnd., vol. 20, p. 88, pi. 1, figs. 1-10: pi. 2, figs. 



