254 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55, 



b.^ Dorsal processes present on more than one segment. 



c.^ Processes on segments II to VIII, inclusive. P. disticJius Mooro. 

 c." Processes on segments III, IV, V, and VIII (Moore,* not seen). /*. 

 alcicornus Rloore. 

 hj' Processes on segment VIII only. P. mc.cicaiiUK, new species. 

 a.^ Dorsal portions of several segments elevated; segments VII and VIII, with 

 funnel-shaped enlargements of the dorsal portions; funnel of segment 

 VIII excavated dorsally so that its dorsal margin bears two small " horns." 

 P. dnrhini, nev,' species. 



PTERODRILUS DISTICHUS Moore. 



Ptcrodrilus distichus Mooke, Proc. Acad. Nat. Sci. Phila., pp. 453-454, pi. 

 13, tigs. 2, 2a-2d, 1S94 (western New York on Camharus barto7iii 

 (Fabricius) ). 



Specimens.— 2b (2=Cat. No. 17651, U.S.N.M.), Oxford, Ohio 

 (S. K. Williams) , host not given; 20 (10= Cat. No. 17G52, U.S.N.M.), 

 Cedar Point, Ohio (S. R. Williams), host not given; 50 (15=Cat. 

 No. 17653, U.S.N.M.), White Eiver, Irondale, near Anderson, In- 

 diana, August, 1915 and 1916 (M. M. Ellis), on Camharus rusticus 

 Girard (det. Faxon) ; three. White River, Noblesville, June 23, 1915 

 (M. M. Ellis), on Camharus rusticus Girard. 



PTERODRILUS MEXICANUS, new species. 



Type.—QdX. No. 17654, U.S.N.M., body length 1.0 mm., Mirador, 

 State of Vera Cruz, Mexico (Nelson and Goldman), on Canibarus 

 mexicanus Erichson. 



The type-specimen was unique, and, unfortunately, poorly pre- 

 served. Consequently but a brief diagnosis can be given. General 

 body form similar to Pterodrilus distichus Moore; no dorsal proc- 

 esses on segments II to VII, inclusive; segment VIII bearing a sim- 

 ple four-horned appendage like that on the same segment of P. dis- 

 tichus; dental formula 5—1; upper jaw type IX, lower jaw^ type X. 

 As far as the internal anatomy could be traced in a whole mount this 

 poorly preserved specimen the organs resembled those of P. distichus 

 Moor and P. durbini, new species. 



PTERODRILUS DURBINI, new species. 



Plate 11, fig. 1. 



Type.— Cat No. 17655, U.S.N.M., body length 1.5 mm.. White 

 River, Irondale, near Anderson, Indiana, August, 1916 ( M.M. Ellis), 

 on Camharus rusticus Girard (det. Faxon). 



Paratypes.—T^xo, Cnt. No. 17655, IT.S.N.M., and 10 others col- 

 lected with the type. 



Description. — Body rather short and thick, size small; width of 

 the head scarcely equaling the width of segment I; body segments 

 increasing rapidly in diameter from segment I to segment VII ; seg- 



iProc. Acad. Nat. Sci. Phila., 1S93, p. 450. 



