164 



cylindrical, about twice as long- as its greatest diameter, with distinct 

 protruding collar. Spermathecre wnth duct and ampulla distinctly 

 differentiated; ampulla simple, thin-walled, pear-shaped, and devoid 

 of diverticula; junction with the digestive tract on the dorsal surface 

 of latter but distinct from corresponding' junction of opposite sper- 

 matheca ; duct about twice as long- as ampulla, wath no glands at ectal 

 opening. 



Described from ten sexually mature specimens. Type and para- 

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

 of Professor Frank Smith. 



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

 lected near Urbana, Illinois, April i, 191 1. They were all in a very 

 restricted locality in undisturbed forest-land, under the decaying 

 leaves, and at a slight depth in the rich moderately moist humus. The 

 majority of the specimens collected were sexually mature. 



Affinities. — The structure of the spermathecje puts this form into 

 the group of species having no diverticula on the ampulla. There 

 are at present but six representatives of this group in North America, 

 the majority of them being found in Europe. This worm evidently 

 has no close relatives among the foreign forms since the differences 

 existing between them are numerous and well marked. Of the six 

 American species, only two, F. alba Aloore and F. parra Moore (^F. 

 bulhosa Rosa?), appear to be at all closely allied to F. siiiia, and both 

 of these show several distinct differences from the new species. 



EXTERNAL CHARACTERS 



The body is slender, cylindrical, and tapers from XII or XIII 

 gradually towards the two extremities. The length varies from 15 

 to 19 mm. The diameter is greatest in the region of the clitellum and 

 varies from 0.45 to 0.57 mm. The color of the living worm is whitish 

 with a slight tinge of yellow. The intersegmental grooves are ob- 

 solete in all parts of the body except in the extreme anterior region, 

 where the first of these grooves and sometimes the second and third 

 grooves are well marked. The somites vary from 52 to 58. The 

 clitellum is on XII-^XIII and is well developed. The prostomium 

 (PI. XI, Fig. 47) is prominent and pointed. It varies slightly in 

 shape, but the typical form is that indicated in the figure. In one 

 or two of the specimens examined the prostomium was shorter and 

 more rounded, but it is possible that this difference was due to a con- 

 traction of the specimens. The set^ are of the typical Fridericia type. 

 They are well developed, and the greater part of their length pro- 



