38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



2. (s) Esophagus long, with the middle part of uniform 



or nearly uniform diameter. 



3. (4) Female genitalia double Cosmocercinae 



4. (3) Female genitalia single, extending anteriorly Atractinae 



5. (2) Esophagus short, with the middle part forming an 



elongated ovaloid bulbus. Females with spines ..Carnoyinae 



6. (i) Esophagus with its three parts of nearly uniform 



diameter, thick and short Rhigoneminae 



The subfamily Cosmocercinae (= Cosmocercidae Travassos, 

 1930) is here understood in the same way as was the corresponding 

 family by Travassos, separating it thus from the one-spiculed forms. 

 The Atractinae (=Atractidae Travassos) are separated from the 

 Cosmocercinae because of the single female genitalia, but the inales 

 are so similar in both groups, and the separating character so sec- 

 ondary in most other families of Nematoda, that I have no doubt 

 that both groups should be classified more closely than is done by 

 most authors. Two groups from invertebrates must be added to 

 them, ( I ) the Carnoyinae, highly specialized forms from Myriapoda 

 and Oligochaeta, with a peculiar development of the esophagus and 

 with sexual dimorphism, the females with spines in the anterior part 

 of the body, and (2) the Rhigoneminae which have a short thick 

 esophagus with all its three parts of nearly the same diameter. 



Subfamilies and Genera of the Family Heterakidae 

 Subfamily Subulurinae. 

 Subfamily Heterakinae. 



KEY TO subfamilies OF HETERAKIDAE 



1. (2) In males the precloacal sucker or pseudosucker 



without a chitinous rim Subulurinae 



2. (i) In males the precloacal sucker well defined with a 



chitinous rim Heterakinae 



The outlines of the family and both subfamilies are accepted as 

 by Baylis and Daubney (1926). Both subfamilies are united by 

 some transitions. The suckers of the second subfamily are undoubt- 

 edly a development of the pseudosuckers of the first one. Travassos 

 (1930) proposed to separate the Spinicaudinae, a proposal which un- 

 doubtedly has some grounds. The genera included here are poly- 

 myarian and have feebly developed lips, a character which separates 

 them from the following family. 



Subfamilies and Genera of the Family Kathlaniidae 

 Subfamily Kathlaniinae. 



Genera: Oniscicola Schwenck, 1927; Crusnema Artigas, 1926. 



