352 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lu 



Hall, 1914, Proc. U.S. Nat. Mus., vol. 48, p. 190.— Goodnight, 1940, Illinois 

 Biol. Monogr., vol. 17, no. 3, p. 31 (description only); 1940, Rep. Reelfoot 

 Lake Biol. Station, vol. 4, p. 171 (?South Dakota record). — Holt and Hoff- 

 man, 1959, Journ. Tennessee Acad. Sci., vol. 34, p. 97, figs. 1-6 (redescription 

 of species). 



Type specimens. — Holotype and two paratypes, USNM 53794, 

 from Cambarus diogenes collected at Boulder, Boulder County, 

 Colorado, by Max M. Ellis. 



Diagnosis. — A moderately small member of the genus, differing 

 from other members of the Philadelphica group by the combination 

 of the slender, elongate outline of both body and head, the large 

 anisomorphic subequal jaws; entire peristomial margin; relatively 

 large bursa in comparison with the long, slender spermiducal gland, 

 and shortened prostate gland. The ectal spermathecal duct is much 

 longer in relation to size of the ental bulb than in the other related 

 species. 



Description. — A distinctly slender and graceful worm, the body 

 only slightly thicker at maximum diameter than at the narrowest part, 

 tapering more distinctly caudally down to the small caudal sucker, its 

 diameter less than that of either head or segment i. Segments less 

 than twice as long as broad, the length almost equally divided into 

 prosomitc and metasomite, the former not at all larger in diameter 

 than the latter. 



Head rather long and narrow, about equal to first three segments 

 combined, its greatest diameter a little greater than that of segment i. 

 Peristomium set off by a basal constriction, not evidently flared, the 

 margin divided into dorsal and ventral halves but neither half with 

 lobes or tentacles. 



Jaws large and massive, sub triangular in dorsal aspect, aniso- 

 morphic, heterodont, the dental formula 5-4; dorsal jaw slightly 

 larger than ventral in lateral aspect, its median tooth subequal to the 

 paramedian teeth of the ventral jaw. 



Male reproductive system of moderate size, occupying half of one 

 side of the coelom of segment vi or less, the bursa elongate pyi'iform, 

 its greatest diameter near the ental third mstead of near the midlength 

 as m related forms; ejaculatory duct short, about equal to bursal 

 diameter. Spermiducal gland slender and elongate, oriented almost 

 horizontally in striking contrast to the oblique dorsoventral position 

 taken by the gland in most other related species, increasing slightly in 

 diameter entally, with the ental fourth of the length bent a little 

 ventrad. Deferent lobes small or absent. Prostate about two- 

 thirds as long as spermiducal gland and from one-fourth to one-half 

 its diameter, extending along the dorsal side entally about as far as the 

 entry of the posterior deferent duct. 



