630 



dorsal and lateral surfaces. Prostomium slightly pointed. Head 

 pore on o/I. Cuticnla very thick and resistant. Lymphocytes few 

 in number, oblong, nucleated, cytoplasm heavily granular in appear- 

 ance. Brain about twice as long as wide; anterior margin conical, 

 posterior margin emarginated, lateral margins convergent anteriorly. 

 Peptonephridia lacking. No ventral glands. Septal glands in IV- 

 VI. Dorsal vessel arises in XIII. Blood yellowish. Anteseptal part 

 of nephridium a mere nephrostome; postseptal part large, flattened 

 laterally, efferent duct arising from its ventral side near posterior 

 end. Spermatheca with distinct duct and ampulla; ampulla pear- 

 shaped ; not connected with the intestine and with no diverticula ; 

 duct narrow, rather short, with no glands at ectal opening. Length 

 of spermiducal funnel about twice its diameter. Testes undivided; 

 sperm sacs lacking. 



For a discussion of the penial Ijulb see page 632. 



Described from five sexually mature specimens, although a num- 

 ber of others were examined in connection with the study on the 

 living forms. The type and a paratype are in the collection of the 

 junior author, and paratypes in that of the senior author. 



The above specimens which fomi the basis of the description of 

 this species were found in the mud and settlings in the bottom of 

 the waterworks reservoir of Urbana, Illinois. At the time of col- 

 lection they occurred only in moderate numbers. The dates oi col- 

 lection range from October 23 to November 26, J895. The species 

 name is given in recognition of the discoverer. Miss Bertha V. H. 

 Forbes. 



EXTERNAL CHARACTERS 



The specimens are small, their length being only 5-6 mm. The 

 figures given are for the living specimens and apply to all the sexually 

 mature individuals. As measurements of alcoholic material gave al- 

 most exactly the same result, it appears that in this species of the 

 Bnchytrccidcc authentic data regarding length can be secured from 

 the examination of preserved material. This fact may be due to 

 the exceptionally thick and resistant cuticula, which may perhaps 

 also account for the fact that living specimens have but a slight range 

 in contraction and extension. The number of somites varies from 

 25 to 28. The body is cylindrical, and the diameter is approximately 

 uniform for almost its entire length, only the first somite and the last 

 two or three showing gradual increase in size. The diameter varies 

 from 0.22 to 0.24 mm. The clitellum is on XII-XIII and is slightly 

 developed dorsad and laterad but is interrupted on the ventral sur- 

 face of the body. The prostomium (PI. CI, Fig. 29) is rounded, yet 



