258 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 55, 



Fig. 14.— Upper jaw 

 of t y p e-specimen 

 of cambarincola 

 vitrea ellis, from 

 douglas lake, mich- 

 igan, anterior face 



VIEW. 



Grapevine Point, Douglas Lake, Michigan, summers of 1914, 1915, 

 and 1916 (M. M. Ellis), on GamhaTus proplnquus Girard; 10 (2-Cat. 

 No. 17675, U.S.N.M.), Wellington, Illinois, September, 1914 (A. T. 

 Evans), on Camharus virilis Hagen (det. Faxon); 15 (3-Cat. No. 

 17676, IJ.S.N.M.), Urbana, Illinois (Frank Smith), on Cambarus 

 virilis Hagen; 20 (2-Cat. No. 17677, U.S.N.M.), Arikaree River, near 

 Beecher's Island, Colorado, October, 1915 (B. Jaffa), on Camharus 

 virilis Hagen; three (2-Cat. No. 17678, U.S.N.M.), St. Marys River, 

 Fort Wayne, Indiana (host not given) ; two (1-Cat. 

 No. 17679, U.S.N.M.), mouth of Carp River, St. 

 Martins Bay, near Straits of Mackinac (IT. T. Sco- 

 vell), on Camharus virilis Hagen. 



Description. — Body and head subterete, little if 

 at all depressed; diameter of the head approxi- 

 mately equal to that of segment II, usually slightly 

 greater than that of segment I; body segments II 

 to VIII subequal, segments V. VI, and VII when 

 distended with sex cells slightly wider than seg- 

 ments III and IV; segments posterior to VIII narroAving rather 

 rapidly to the caudal sucker, the diameter of which is less than of 

 the head; all body segments easily visible in side view; major annu- 

 lations distinct, but very slightly elevated above the minor annula- 

 tions; head divided into three subequal parts, the anterior being the 

 most distinct of the three; lips two, subequal, each with a small, 

 median emargination ; major pharyngeal diverticula two, the dorsal 

 slightly anterior to the ventral ; a few short bristles 

 present on each lip; dental formula 5-4, vipper jaw 

 between types V and VII, lower jaw of general 

 plan of type VIII but with all four teeth almost 

 subequal; alimentary canal straight, following the 

 mesial line of the body, maximum enlargement in 

 segment IV; anterior nephridia opening to the out- 

 side through a common pulsatile pore on the dorsal 

 surface of the major annulation of segment III; 

 spermatheca simple and tubular; testes present in 

 segments V and VI vasa deferentia from segments V and VI, meet- 

 ing the atrium in segment VI ; accessory sperm tube present ; largest 

 specimen examined, 4.7 mm. 



This species superficially resembles Xironodrilus formosus Ellis, 

 both in body form and type of jaws. In addition to the several 

 generic characters by which these two species may be separated, it 

 may be noted that the jaws, although having the same number of 

 teeth and the same general form, are quite different. (See figures.) 



\ 



Fig. 15.— Lower jaw 

 of type-specimen op 

 cambarincola vit- 

 rea ellis, from 

 douglas lake, mich- 

 igan, anterior face 



VIEW. 



