PARASITIC ROUNDWORMS 541 



21 (18) No conical spicules behind cloacal aperture; caudal lobes -cylin- 



drical Gordius platycephalus Montgomery 1898. 



For female of this species consult 30 in this key. 



Male up to 216 mm. long, i mm. broad. The flattened 

 anterior end is characteristic, but Montgomery found one 

 specimen apparently of G. densareolatus with this feature and 

 could explain it only as a hybrid form. Canada, Pennsyl- 

 vania, and Guatemala. 



FIG. 842. Gordius platycephalus $ head and tail in ventral 

 aspect. Magnified. (After Montgomery.) 



22 (n) Caudal end straight, not enlarged nor lobed. 



(Females of Gordius) . . 23 

 Compare 5 in key. 



23 (24) No elevated cuticular areoles on surface of body. 



Gordius villoti Rosa 1882. 



For male and range of this species consult 14 in this key. 



Largest female 705 mm. long, 1.9 mm. broad. One variety (G. villoti difficilis Mont- 

 gomery) has cuticular areoles at the ends of the body only. The other varieties are like the 

 males marked with light spots or plain. Montgomery found some points of difference from 

 the European type, and the American form may prove on further study to be a separate 

 species. 



24 (23) Elevated cuticular areoles cover the entire surface of the body. 25 



25 (26) Paired dark stripes occur in median lines. 



Gordius leidyi Montgomery 1898. 



Male of this species is unknown. Female 

 295 mm. long, 1.5 mm. broad. Sharply dis- 

 tinguished from all other species in the genus 

 by the peculiar truncated form of the posterior 

 end and the two narrow parallel stripes of 

 intense reddish brown in the median line of 

 the dorsal groove. 



In the Leidy collection; source unknown. 



FIG. 843. Gordius leidyi <J> ; head and tail in dor- 

 sal aspect. Magnified. (After Montgomery.) 



26(25) Dark stripes in median lines arc lacking. . , , ,. . . . ... . . 27 



The unknown female of Gordius longareolatus probably falls here. 



2 7 (3) Areoles not elongated in long axis of body; head not flattened. . 28 



28 (29) Areoles close-set, tending to produce longitudinal ridges. 



Gordius lineatus Leidy 1851. 



For male and range of this species consult 16 in this key. 



Female up to 283 mm. long, 0.8 mm. broad; like male very slender. Deeper buff color as 

 against the pale, transparent yellowish white of the male. In the female the cloacal orifice is 

 surrounded by a narrow reddish-brown ring. 



29 (28) Areoles more or less confluent, tending to produce transverse rows; 



head usually cylindrical. 



Gordius densareolatus Montgomery 1898. 

 For male and range of this species consult 19 in this key. 



Female up to 395 mm. long, 1.7 mm. broad. Body robust. Head white, followed by light 

 buff ring and broad reddish brown ring; cloacal pore surrounded by thin black ring and broader 

 circular reddish brown area; body generally chocolate or yellowish brown. Cloacal aperture 

 in a ventral depression. 



