24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



coarse, plain striation of the cuticle, coarser behind the head, is a 

 common character of all of the latter. The horseshoe-shaped am- 

 phid is quite like that of Ceramonenia. The tail is typically chroma- 

 doroid, the spicules similar to those of Desmodora. The esophagus 

 of Draconema with its two swellings is quite distinctive, but Noto- 

 chaetosoma has an ordinary unibulbar esophagus. The adhesive 

 setae of these forms, concentrated in two regions, on the head and 

 in the preanal region, are peculiar. Steiner ( 1926) proposes to treat 

 the Epsilonematidae (fig. 47), with the solid adhesive setae, sepa- 

 rately from the Draconematidae, with the tubular ones each con- 

 nected with a gland which is probably a cement gland. Although 

 agreeing with his principal idea, the writer could hardly ascribe to 

 them a rank more elevated than that of a subfamily, the close con- 

 nection with the Desmodorinae not justifying their separation. 



Order DESMOSCOLECATA 



Families and Genera of Desmoscolecata 

 Family Desmoscolecidae. 



Genera: Eudesmoscolex Steiner, 1916; Desmoscolex Claparede, 1863; 

 Quadricoma Filipjev, 1922; Tricoma Cobb, 1893. 

 Family Greeffiellidae. 



Genus: Greeffiella Cobb, 1922 (syn. Trichoderma Greeff, 1869, preocc). 



KEY TO FAMILIES OF DESMOSCOLECATA 



1. (2) Setae not very numerous, body having a naked ap- 



pearance. Secreted rings usually present ..Desmoscolecidae 



2. (i) Setae and nerveless spines very numerous, the 



body having a hairy appearance. Secreted rings 



absent Greeffiellidae 



This order includes a group, comparatively small as yet, of ma- 

 rine forms. The most characteristic feature is their cuticle with its 

 very prominent chitinous rings, from 12 to nearly 84 in number. 

 They have the appearance of body segments and have led to a com- 

 parison of these forms with the annelids, but they are purely exter- 

 nal or even secreted, having no relation to the internal organs (figs. 

 49, 50). The large amphids are very prominent. The strong setae 

 of the body constitute a development in connection with the peculiar 

 mode of locomotion, the nematodes traveling on them as on stilts, 

 the dorsal side downward. Interesting also is the habit of bearing 

 the eggs fastened on the outside of the female body. Very little is 

 known about the inner organization of these forms, not even whether 

 they have straight or reflexed ovaries. It is a very isolated group 

 with a somewhat uncertain systematic position. 



