20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



The Plectidae are mostly terrestrial or fresh-water nematodes 

 with only a very few marine genera. All genera have prominent 

 spiral amphids of somewhat aberrant type in a posterior position 

 (fig. 27). In the tail there are caudal glands and spinneret; the tail 

 is mostly of the typical chromadoroid form. Many forms are inter- 

 esting biologically on account of their ability to revive after com- 

 plete desiccation. The generic analysis of this group seems to be as 

 yet far from being finished. 



Subfamilies and Genera of the Family Chromadoridae 

 Subfamily Cyatholaiminae. 



Genera: Necticonema Marion, 1870; Cyatholaimus Bastian, 1865; Prae- 

 acanthonchns Micoletzky, 1924; Seuratiella Ditlevsen, 1921 (syn. 

 Seuratia Ditlevsen, 1919, preocc); Paracanthonchns Micoletzky, 

 1924; Acanthonchus Cobb, 1920; Paracyatholaimiis Micoletzky, 1924; 

 Longicyatholaimus Micoletzky, 1924; Statenia Allgen, 1930; Nannon- 

 chus Cobb, 1913 ; Achromadora Cobb, 1913; Pomponema Cobb, 1917; 

 Nannolaimns Cobb, 1920; Ethmolaimus de Man, 1880; Odontolaimus 

 de Man, 1880; Prodesmodora Micoletzky, 1923; Anatonchium Cobb, 

 1920. 

 Subfamily Choanolaiminae. 



Genera: Denionema Cobb, 1893; Biilhopharyngiella Allgen, 1929; Chonio- 

 laimus Ditlevsen, 1919; Cobbionema Filipjev, 1922; Zygonemella 

 Cobb, 1920; Zalonema Cobb, 1920; Choanolaimiis de Man, 1880: 

 Anonchus Cobb, 1913; Halichoanolaimus de Man, 1886; Smalhundia 

 Allgen, 1929; Gammanema Cobb, 1920; Trogolahnus Cobb, 1920; 

 Selachinema Cobb, 1915; Pseudonchus Cobb, 1920; Synonchium Cobb, 

 1920; Cheironchus Cobb, 1917 (syn. Dignathonema Filipjev, 1918). 

 Subfamily Richtersiinae. 



Genera: Richtersia Steiner, 1916; Richtersiella Kreis, 1929. 

 Subfamily Chromadorinae.^ 



Genera: Etichromadora de Man, 1886; Odontocricus Steiner, 1918; Dicri- 

 conema Steiner and Hoeppli, 1926; Rhabdotodernia Marion, 1870; 

 Fusonema Kreis, 1928; Actinonema Cobb, 1920; Rhips Cobb, 1920; 

 Neochromadora Micoletzky, 1924; Prochromadora Filipjev, 1922; 

 Prochromadorella Micoletzky, 1924; Spiliphera Bastian, 1865; Delta- 

 nenia Kreis, 1929; Chroniadorina Filipjev, 1918; Chromadorella Filip- 

 jev, 1918; Spilophorella Filipjev, 1918; Chromadorissa Filipjev, 1917; 

 Graphonema Cobb, 1898; Pimctodora Filipjev, 1929; Hypodontolaimiis 

 de Man, 1886 (syn. lotadoriis Cobb, 1920) ; Ptycholahnellus Cobb, 

 1920; Oistolaimus Ditlevsen, 1921 ; Odontonema Filipjev, 1929; En- 

 dolaimus Filipjev, 1922; Chromadorita Filipjev, 1922. 

 Subfamily Desmodorinae. 



Genera: Desmodora de Man, 1889; Amphispira Cobb, 1920; Xenonema 

 Cobb, 1920; Bolbonema Cobb, 1920; Micromicron Cobb, 1920; Eute- 



2 Kreis (1929) proposed some generic or subgeneric groups, for which he 

 did not propose types, as foUow^s : Macro chromadora (for a part of Prochro- 

 madorella) ; Dichromadora, Trichromadora (for parts of Chromadora) ; 

 Chromarina (possibly synonymous with Punctodora). 



