8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



All these have a smooth cuticle, except for only a ver>' few forms 

 which have a very fine striation. The esophagus is uniform, without 

 a bulb (fig. i). The head presents a typical structure, bearing the 

 typical six labial papillae, ten cephalic setae, in some forms trans- 

 formed into papillae, and two amphids (figs. 4, S), the latter present 

 in the form of a pocket, with an anterior aperture (figs. 2, 3, 4) ; the 

 cuticle on the head presents a very typical reduplication with a circu- 

 lar cavity around it, bordered behind by the so-called cephalic line 

 (figs. 2, 4) ; the esophagus adjoins the inner layer of the cephalic 

 cuticle along a very wide surface (figs. 2, 3). The ovaries are always 

 reflexed (fig. i). The musculature is polymyarian. Some of these 

 nematodes are the largest of all free-living nematodes. There are 

 exceptions to nearly all these characters inside the order, but most 

 of these are present in any given form discussed here. 



KEY TO FAMILIES OF ENOPLATA 



1. (2) Cuticle with duplication on the head. Males mostly 



with one or two preanal tubes. Most genera marine 

 Enoplidae 



2. (i) Cuticle without duplication on the head. 



3. (6) Esophagus with muscles. Free-living forms. 



4. (5) Esophagus strong, of nearly uniform thickness through- 



out its whole length. Free-living, fresh-water and 



marine forms Trilobidae 



5. (4) Esophagus dorylaimoid, i.e., bottle-shaped, weak, 



almost without musculature anteriorly, then sud- 

 denly enlarged and strongly muscular posteriorly. 

 Free-living, mostly fresh-water and soil forms, some 

 marine forms Dorylaimidae 



6. (3) Esophagus without muscles, forming a long narrow 



chitinous tube with some adhering, large, epidermal 

 cells. Adults mostly free-living, soil and fresh-water 

 forms ; larvae parasitic in insects and other in- 

 vertebrates Mermitidae 



Subfamilies and Genera of the Family Enoplidae 



Subfamily Leptosomatinae. 



Genera: Anticoma Bastian, 1865 (syn. Stenolaimus Marion, 1870) ; 

 Leptosomella Filipjev, 1927; Barbonema Filipjev, 1927; Platycoma 

 Cobb, 1893; Platycomopsis Ditlevsen, 1926 (syn. Dactylonema 

 Filipjev, 1927); Synonchiis Cobb, 1893 (sg. Fiacra Southern, 1914; 

 sg. Jdgerskioldia Filipjev, 1916) ; Cylicolaimus de Man, 1889; 

 Nudolaimus Allgen, 1929; Leptosomatnm Bastian, 1865; Leptoso- 

 matides Filipjev, 1918; Deontostoma Filipjev, 1916; Thoracostoma 

 Marion, 1870 (sg. Psendocella Filipjev, 1927) ; Triodonfolaimiis 

 de Mail, 1893. 



