8 PROCEEDINGS OF THE NATIONAL MUSEUM VOL, 125 
a treatment of the anatomy of the species that will serve to introduce 
the reader more fully to features common to all species of the genus 
and as a basis for the shorter descriptions of the other species of 
Pterodrilus that follow. 
Ficure 1.—Pvrerodrilus alcicornus: a, lateral view of reproductive systems; b, animal from 
Giles County, Va. (b=bursa; ejd=ejaculatory duct; pr=prostate; sb=bulb of sper- 
matheca; sd=spermathecal duct; sg=spermiducal gland; vd=vas deferens.) 
