504 



FRESH-WATER BIOLOGY 



FIG. 809. Mesomermis mrginiana. 



a, mouth opening; b, anterior circlet cephalic papillae; c, posterior circlet 

 cephalic papillae; d, pharyngeal tube; e, outer margin lateral organ;/, strands, 

 lateral organ; g, esophagus; h, papilla; *, unicellular organs of unknown signif- 

 icance; j, nerve-ring; k, esophagus; /, intestine; m, ejaculatory duct; n, body 

 wall; o, one of the oblique copulatory muscles; p, one of the submedian sup- 

 plementary organs; q, one of the ventral supplementary organs; r, spiculum; 

 j, one of the caudal ventral supplementary organs; t, subventral caudal sup- 

 plementary organ. (After Cobb.) 



X 120 



FIG. 810. Mesomermis virginiana. 



a, mouth opening; b, lateral organ; c, esophagus; d, nerve-ring; e, posterior end esophagus; /, intestine; 

 g . blind end anterior testicle; h, testicle; i, junction of testicles; j, intestine; k, blind end posterior 

 testicle; I, ventral supplementary organs; m, submedian supplementary organs; , oblique copulatory 

 muscles; o, spiculum. (.After Cobb.) 



