FREE-LI\^NG NEMATODES 



;oi 



6i (60) Form of cavity various, closed in front, amphids opposite it. . (ji 



62 (63) Lateral organs or amphids inconspicuous Trilolnis Bastian. 



Fresh -water genus of which about half a dozen species are known. Known to fee.l u[xjn 

 diatoms in one case and upon rotifers in anotlier. Hermaphroditism occurs. 



Representative species Trilobus longus {W\i\y) 1)^,-^1. 





source of nourishment of this species, 

 about one-fourth as wide as the body. 



The lips bear papillae but their numlier i.<i not 

 „ known. The intestine frequently contain.s rliatoms 

 in large numbers, indicating that these are a comm<jn 

 The longiitudinal fields are distindly develoi)cd, and 

 From the slightly elevated vulva the vagina leads in- 

 ward at right angles to the ventral surface fully half way across the body. The rcllexwl 

 ovaries pass about two-thirds of the way back to the vulva. Two or tiiree eggs may <Kcur in 

 each uterus at one time. These are somewhat ellipsoidal and thin shelled, being al)out two- 

 thirds as long as the body is wide and about two-thirds as wide as long. The eggs ap[X'ar to 

 pass through at least the early stages of segmentation before being deposited. The waits of 

 the vagina present the peculiarity of being very thick, and composed of six to .seven tun- 

 centric layers so that the organ is considerably broader than it is deep. Its intcrnAl wall 

 presents the peculiarity of staining strongly with carmine. 



Trilobus longus, the only American fresh-water nematode outside the Mcrmithidac that had 

 been adequately characterized previous to the inception of this chapter, was de.scribed by the 

 famous Philadelphia naturalist, Dr. Joseph Leidy, in 185 1. At that time extremely little wa^ 

 known about the free-living fresh-water nematodes, and no one dreamed of their vast numlxrr 

 and variety. The peculiar male supplementary organs of Trilobus did not fail to attract atten- 

 tion, and it is owing to this fact that Leidy's name is associated with the striking sp)ecic3 

 selected as a representative of the genus. 



Habitat: Mud about the bases of aquatic plants, in pools, ditches, rivers, and lakes through- 

 out the country. 



Trilobus longus. 



T, male; II, head, lateral view; III, head, lateral view; IV, head, ventral view; V. anterior supple- 

 mentary organ; VI, posterior supplementary organ; VII, two supplementary organs from an exceptional 

 female. 



a, lateral seta; b, papilla; c, submedian seta; d. pharynx; r, lateral organ; /, toiUh; .c. toj)lh; *• «^Jj|J': 

 agus; /, nerve-ring; i, excretory pore; k, body muscles; /, glandular!?) organs; w. intestine; «• W'"'| 

 end anterior testicle; 0, testicle; p, junction of testicles; q, blin.l-cnd posterior testicle; r. va> *>^'^'^: 

 5, nerve of supplementary organ; t, cavity of supplementary^ organ; u, left spiculum r. acccs^ r> piece, 

 w, the three caudal glands; x, anus; y, terminus; z, aix-x of supplementary organ. K.\\\cx Couu.; 



