538 FRESH-WATER BIOLOGY 



2 (5) Caudal end slenderer than preceding region of body, with tendency to 



roll into spiral form (Males of Chordodes) . . 3 



The cloacal orifice is ventro-median and the ventral surface possesses a shallow furrow or 

 groove from this orifice to the posterior extremity. 



3 (4) Cuticular areoles longer than high; small circular pits upon and be- 



tween them. . . Chordodes occidentalis Montgomery 1898. 



For female of this species consult 6 in this key. 



Male up to 255 mm. long, 1.5 mm. broad. Color light brown to 

 black; tip of head yellowish white. A western species; Montana, 

 Wyoming, California, Arizona, Texas, Mexico. 



An Acridiid is known to serve as host for this species. 



FIG. 833. Head and surface areoles of Chordodes occidentalis . Highly 

 magnified. (After Montgomery.) 



4 (3) Cuticular areoles higher than long. 



Chordodes morgani Montgomery 1898. 



For female of this species consult 7 in this key. 



Male 64 to 220 mm. long. Color dull chocolate brown, except anterior end which is always 

 white. Papillae of several types; the most regular conical with short spine, and the highest 

 papillae with a few spines on the summit of each being typical. 



The species manifests a high degree of individual and sexual variation. Recorded from 

 Pennsylvania, Maryland, Michigan, Ohio, Florida, Iowa, and Nebraska. C. puerilis, origi- 

 nally described from two males, belongs here. 



A Blattid is known to serve as host for this species. 



FIG. 834. Cuticula of Chordodes morgani Q F . IG - 8 35- Cuticula of Chordodes morgani 



in transverse section. Highly magnified. (After $ in transverse section. Highly magnified. 



Montgomery.) (After Montgomery.) 



5 (2) Caudal end swollen, somewhat knob-shaped; also marked off by a 



slight constriction. No tendency to roll into a spiral. 



(Females of Chordodes) . . 6 



The females of Gordius, which may easily be confused with these, never have more than a 

 slight swelling at the caudal end and this is not marked off by a constriction. 



6 (7) Cuticular areoles longer than high; small circular pits upon and be- 



tween them . . Chordodes occidentalis Montgomery 1898. 



For male and range of this species consult 3 in this key. 



Anterior region much attenuated; head pointed. Areoles low. Color yellowish brown with 

 darker neck ring and black mouth spot. 



7 (6) Cuticular areoles higher than long. 



Chordodes morgani Montgomery 1898. 



For male and range of this species consult 4 in this key. The variable papillae are also 

 noted there. 



Female up to 222 mm. long. In the largest females the cuticula in surface view is like that 

 of the males, except that the large papillae are less numerous. Color averages lighter than in 

 the male. 



