NO. 6 CLASSIFICATION OF NEMATODES — FILIPJEV 35 



body of the host, in the soil, the burrows of wood-eating beetles, etc. 

 The males reach full maturity, but the females have the ovary unde- 

 veloped and without direct connection with the uterus; the vulva 

 is open. Then copulation takes place, the males die, and the fer- 

 tilized female goes through the skin of a new host into the body, 

 where it grows to the mature parasitic stage. 



The Hoplolaiminae should be treated as a separate subfamily 

 (fig. 68). The cuticle has peculiar rings, sometimes subdivided to 

 give a scalelike appearance. There is a peculiar huge spear with 

 proximal knobs. It is a highly specialized terrestrial group. 



Family STRONGYLIDAE 



The Strongylidae must be placed as a third family of this order. 

 This large parasitic group was considered as a family long ago ; now 

 it is usually recognized as an order. The first-stage larvae are very 

 distinctly similar to some free-living forms of the genus Rhabditis. 

 The two dilatations of the esophagus, the posterior one with a mas- 

 ticatory apparatus, and the cylindroid mouth capsule are very similar 

 to Rliabditis. The free life of strongylid larvae, and their molts 

 with the ensheathed migratory third stage, correspond strictly to that 

 described by Maupas in Rhabditis. Even in the adult stage, the 

 characteristic bursa in typical cases, with its 20 rays, is comparable 

 to that of some species of Rhabditis (cf. figs. 62, 63, and 70). 



A systematic conclusion from these very real similarities could 

 only be similar to that arrived at in analogous circumstances by the 

 carcinologists in placing the aberrant Rhizocephala in the order Cir- 

 ripedia, and, similarly, the parasitic copepods with the free-living 

 forms in the Copepoda. 



Order OXYURATA 



The Oxyurata with their tripartite esophagus and masticatory 

 cardiac bulb could be compared with the free-living Anguillulata. It 

 is even difiicult to find clear diagnostic characters to separate these 

 two orders. Steiner (1923) described a parasite from a sawfly larva 

 and because of its general similarity he referred it to the oxyurid 

 genus Aplectana with all its other species intestinal parasites of Am- 

 phibia and Reptilia. (Now it is referred to a separate genus, Steincr- 

 nema.) The writer found a very closely related species, probably 

 congeneric with Steiner's, in a cutworm, fortunately accompanied by 

 their larvae which proved to be typically rhabditoid ; the influence of 

 parasitism can also give very similar results in both orders, which is 



