504 



FRESH-WATER BIOLOGY 



^ 



m 



mi 



rx 334 , 



Fig. 809. Mesomennis virginian.i. 



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

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

 lateral organ; g, esophagus; h, papilla; i, unicellular organs of uniinown signif- 

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

 wall; 0, one of the oblique copulatory muscles; p, one of the submedian sup- 

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

 5, 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; ;, intestine; k, blind end posterior 

 testicle; /, ventral supplementary organs; m, submedian supplementary organs; », oblique copulatory 

 muscles; 0, spiculum. (.After Cobb.) 



