22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



11. (10) With sharp, longitudinal, cuticular crests along the 



body (differentiated in some as rows of spines). 



Monoposthiinae 



12. (9) Special adhesive setae present in two groups, some 



on the head and some in two or more rows in 

 preanal position. 



13. (14) Adhesive setae in form of hooks without a hollow 



interior Epsilonematinae 



14. (13) Adhesive setae in form of hollow tubes Draconematinae 



The chief distinction between the Chromadoridae and the two 

 Other families is in the eversible mouth capsule of this family. In 

 connection with this the vestibulum becomes twelvefold and com- 

 posed of a soft pliable cuticle. The body cuticle around the mouth 

 also presents a soft portion, the reverse of the cuticular thickening 

 in Plectidae. In all typical forms there is a more or less developed 

 dorsal onchium in the mouth capsule (figs. 31, 32). When the latter 

 is everted, the tooth points forward and functions as an incising or 

 picking organ. Sometimes the tooth is strongly developed and pre- 

 sents a kind of spear, compared by some authors with that of the 

 Dorylaiminae, but its general form and position, dorsal instead of 

 subventral as in the latter, do not permit of considering the two as 

 homologous organs. This typical organization is not clear in the 

 Choanolaiminae where the mouth structures are much more com- 

 plex. In the Desmodorinae several genera show a reduction of the 

 buccal tooth in size, and in some others it may disappear completely. 

 The folds of the soft cuticle around the unarmed mouth of such 

 forms are the only remains of the typical conditions. 



The Cyatholaiminae (figs. 31, 32) have typical spiral amphids, 

 generally with many turns, and a cuticle with very plain rings and 

 transverse rows of points inside. The esophagus is broad, uniform 

 for its full length, and without a bulb except in the somewhat aber- 

 rant fresh-water genera Ethmolaimus, Prodesmodora, and Achro- 

 madora, but the characteristic inner cavity of true bulbs is lacking in 

 these genera. There are 10 cephalic setae in all genera. 



An offshoot of the Cyatholaiminae are the Choanolaiminae, a 

 group of predacious genera, nearly all marine, with the same cuticle, 

 amphids, and tail as in the true Cyatholaiminae (figs. 33-40). Very 

 characteristic are the large cells of the intestine. The mouth struc- 

 tures are specialized in several directions. In Halichoanolaimus 

 there are six true lips and a complex mouth capsule with rows of 

 spines in the form of a comb to retain the nematode's prey inside 

 (figs. 33-35). In CJieironchus there are two jaws (figs. 36-38), 



