154 



Fridericia douglasensis n. sp. 



(PI. IX, Figs. 25, 2^\ PI. X, Figs. 27-34) 



Definition. — Length, 11-20 mm. Diameter, 0.45-0.54 mm. So- 

 mites, 43-55. Color, white. Prostominm short, bhmt, and sHghtly 

 angular at tip. Dorsal pores begin on VII. Setae, 3-6 per bundle in 

 ventral rows and 3-5 in lateral rows in anterior part of the body ; 3-6 

 in middle part, and 2-3 in posterior part. Clitelhim on V< XI-V2 

 XIII. Lymphocytes elliptical. Brain about one and two thirds times 

 longer than wide ; anterior margin concave, posterior margin truncate, 

 lateral margins divergent caudad for greater part of length of brain, 

 then change abruptly to convergent caudad. Peptonephridia large, 

 tubular, slightly tuberculate, unbranched. Dorsal vessel arises in XX. 

 N'ephridia with anteseptal and postseptal parts about the same size; 

 efferent duct arises from middle of latter. Spermiducal funnel well- 

 developed ; length about one and one half times diameter; collar dis- 

 tinctly set ofif from body of funnel by constriction; margin of collar 

 not reflected. Sperm duct shorter than in most species and with few- 

 contortions. Spermathec?e with duct, ampulla, and diverticula; am- 

 pulla funnel-shaped, with 7-1 1 globular, unequal, irregularly disposed 

 diverticula; no glands at ectal opening of duct; each ampulla with 

 independent connection with digestive tract. 



Described from sixteen sexually mature specimens. Many more 

 were examined in estimating the external characters. Type and para- 

 types in the collection of the writer, and paratypes in the collection of 

 Professor Frank Smith. 



The specimens on which this description is based were collected in 

 a deciduous forest near the north shore of Douglas Lake, Michigan, 

 July 14, 191 1. They were found in considerable abundance under 

 chips, pieces of bark, and other debris, at the base of a large fallen 

 tree where considerable moisture was present. 



Affinities. — The species belongs in the group ha\ing more than two 

 diverticula on the spermathecse. It appears to have nO' close relatives 

 among the foreign species and is also distinct from the other American 

 species, apparently approaching none of them closely unless it be F. 

 longa Moore, the description of which is, however, too inadequate to 

 make the establishment of relationships certain. 



EXTERNAL CHARACTERS 



The body is slender and has a length of 11-20 mm. In transverse 

 section its outline is circular, and the diameter is greatest in the region 

 of the clitellum, where it is 0.45-0.54 mm. The living specimens are 



