15 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 59 



The Mermitinae were united in a lone genus, Mermis, until 1901, 

 when Paramerniis was proposed by Von Linstow. An elaborate sys- 

 tem of water forms was proposed by Daday (1913). Steiner in the 

 beginning of his studies rejected Daday's system, but afterwards he 

 adopted all Daday's genera and proposed some of his own, thus elab- 

 orating the existing system. Dr. G. Steiner has in preparation a 

 complete monograph of the family. Some of Cobb's genera are as- 

 signed here with some doubt. 



Order CHROMADORATA 



A smooth cuticle was given as one of the characteristic features 

 in the Enoplata; a coarsely striated one, nearly always typically 

 thickened behind the head, is characteristic for the Chromadorata. 

 The amphid, as in the following order, is primarily spiral, the few 

 exceptions being mostly easily explainable. The ovaries are curved 

 as in the Enoplata. A very characteristic tail (cf. figs, 47, 48) with 

 a long terminal tube is present in most genera. Esophageal bulbs 

 are very common but are not present in all forms. The wide attach- 

 ment of the esophagus to the cuticle is lost except in one form {Der- 

 matolaimus) . The six anterior cephalic setae are very often trans- 

 formed into papillae, so that only the four of the posterior circle are 

 retained as setae. 



KEY TO FAMILIES OF CHROMADORATA 



1. (4) Mouth capsule irreversible, mouth organs very- 



simple, vestibulum unfolded. 



2. (3) Bulb absent; the mouth surrounded by a thicken- 



ing of cuticle; amphids placed far anteriorly. 



Camacolaimidae 



3. (2) Bulb present; the circumoral cuticular thickening 



absent; amphids placed somewhat more poste- 

 riorly Plectidae 



4. (l) Mouth capsule eversible, with a folded vestibulum, 



mostly with a dorsal tooth (with secondary com- 

 plication of buccal organs — teeth, jaws, spines — 

 in one subfamily) Chromadoridae 



Genera of the Family Camacolaimidae 

 Genera: Camacolaimus de Man, 1889 (syn. Acontiolainius Filipjev, 1918; syn. 

 Digitonchus Cobb, 1920; syn. Ypsilon Cobb, 1920); Neurella Cobb, 1920; 

 Halaphanolaimus Southern, 1914; Dermatolaimus Steiner, 1916; Stepha- 

 nolaimus Ditlevsen, 1919; Alaimella Cobb, 1920; Nemella Cobb, 1920; 

 Onchium Cobb, 1920; Onchiilella Cobb, 1920; lonema Cobb, 1920; Crico- 

 laimus Southern, 1914; Dagda Southern, 1914; Aphanolaimus de Man, 

 1880; Par aphanolaimus Micoletzky, 1923; lotalaimus Cobb, 1920; Basti- 



