159 



Fridericia oconeensis n. sp. 



(PI. X. Figs. 35-37; PI. XI, Fi-s. 38-42) 



Dciinition. — Length, 13-17 mm. Diameter, 0.34-0.43 mm. 

 Somites, 44-60. Color, whitish. Prostomium blunt and rounded. 

 Dorsal pores begin on VII. Setje of unequal length, inner ones finer 

 and shorter ; almost straight except for distinct bend at proximal end ; 

 4-6 per bundle for almost entire length of body, sometimes as many 

 as 8 per bundle; 1-4 per bundle in last few somites. Clitcllum on 

 XII-XIII. Lymphocytes numerous, elliptical to circular in outline. 

 Brain about twice as long as wide; posterior margin distinctly con- 

 vex; anterior margin slightly convex; lateral margins divergent 

 caudad. Peptonephridia long, tuberculate, with but few branches, 

 which arise irregtilarly along main part of each organ. Dorsal vessel 

 arises in XX. Nephridia with anteseptal and postseptal parts of about 

 same size ; efferent duct arises from anterior part of latter near septum. 

 Spermiducal funnel with length about twice the diameter, cylindrical, 

 bent near posterior end, with well-marked funnel-shaped collar; duct 

 long, much contorted, and confined to XII. Spermathecse each with 

 pear-shaped ampulla which connects with digestive tract and bears a 

 circle of seven diverticula; duct about twice as long as ampulla; ectal 

 end with a few small unicellular glands. 



Described from six sexually mature specimens. Type and para- 

 types in the collection of the writer. Paratypes also in the collection 

 of Professor Frank Smith. 



The specimens which are the basis of this description were col- 

 lected near Oconee, Illinois, November 5, 1910. They occurred rather 

 abundantly under the decaying bark of fallen timber. Of the total 

 number of specimens collected at that time about one-half were sexu- 

 ally mature. 



Affinities. — This species belongs to the group having more than 

 two diverticula on a spermatheca. A careful comparison of its char- 

 acters with the corresponding ones of the other species of the genus 

 shows that it is a distinct form. It is difficult to compare it with 

 some of the foreign species, since their descriptions are too brief to 

 enable one to determine the relationship with any degree of accuracy. 

 However, no foreign species appears to be closely related to this form. 

 As regards the American species there is only one of them which 

 might be regarded as a near relative, namely, Fridericia tenera Smith 

 and Welch ; and disregarding their minor differences, the characters 

 of the brain and the peptonephridia are sufficient to separate them 

 specifically. 



