34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



duction is to be seen in males of many other plant- or animal-parasitic 

 or semiparasitic species in which the adult male does not feed ; there- 

 fore this reduction is especially confined to males. The peak of the 

 reduction comes in the Sphaerulariinae, parasites of the body cavity 

 of insects. In that group the esophagus and the intestine do not func- 

 tion and the feeding is done through the skin. In some genera the 

 esophagus is still retained, but is always rudimentary and f unctionless ; 

 in others, as in Allantonema and Bradyncma, it is lost completely. 



In the simpler genera of the Diplogasterinae there is an unarmed 

 mouth capsule very similar to that of Rhabditis; in other genera it is 

 armed with a tooth or teeth (fig. 64) different in different genera. 

 The old genus Diplogaster, which, until now, united nearly all the 

 species of the subfamily, must be resolved into several independent 

 genera very distinctly characterized. Some types were given during 

 the last few years by Rahm and Goodey, but the analysis seems to be 

 not yet complete. The earthworm parasite, Ungella, apparently 

 should be placed here; the hooklike onchia could be considered as 

 homologous to the teeth of Diplogaster, and the preneural esophageal 

 swelling is well developed, but there does not seem to be a sharp di- 

 vision between the two parts of the esophagus as in typical members 

 of the Diplogasterinae. 



Tylopharynx, the only genus of the next subfamily, was described 

 by de Man as having three separate rods, united in Tylenchinae into 

 a triple spear, a tylenchoid parallel to the tylencholaimoid Diph- 

 therophora. The recent description given by Goodey (1929) gives 

 a totally different interpretation of the structure of its mouth parts. 

 There are not three, but only two knobs, hollow inside, chitinous 

 ampullae of the esophageal glands. The position of the genus there- 

 fore becomes isolated. 



The Tylenchinae are characterized by a triple spear very like that 

 of Xylene holahnus but mostly with a strongly marked triple enlarged 

 base (fig. 67). 



Here must be located the previously mentioned body cavity para- 

 sites of the insects, the Sphaerulariinae. The more primitive forms 

 like Aphelenehulus, Howardula, and others retain a well-developed 

 spear; Allantonema has lost it, together with the esophagus. Al- 

 though the different genera present some peculiarities in structure 

 and in grade of parasitic reduction, they all have a very peculiar and 

 similar life cycle. The larvae are liberated into the body cavity of 

 the host, they grow inside the host, then leave its body through the 

 anal or genital opening, and after a molt reach maturity outside the 



