AKT. 19 NEW GENUS AND SPECIES OF TEEMATODE LUCKER 5 



group, which most typically represent it, in the opinion of Travassos. 

 Of all these genera, Haplometra as defined by Odhner, is most 

 closely related to the proposed new genus HapJometraiia: on the 

 basis of the existing generic conceptions within the subfamily, the 

 creation of a new genus for the new species from Rana pretiosa is 

 justified and necessary. 



The fact that some of the genera of Plagiorchiinae are extremely 

 closely related morphologically is generally recognized. The char- 

 acters that distinguish the earlier genera, especially those of Looss, 

 Liihe, and Odhner, should, it is believed, be accepted for the pres- 

 ent as a guide, at least until the need for an adequate revision of the 

 group is fulfilled. 



The writer believes that the validity of the proposed new genus 

 Haplometrana depends only upon the demonstration of its distinc- 

 tion from Haplometra; for, as will be shown, the latter genus shares 

 with Haploinetrana^ to a degree, certain characters that distinguish 

 both from all other genera of the subfamily. 



According to Odhner (1911), Looss concluded that the tandem 

 position of the testes in Haplometra cyUndnca Looss was to be re- 

 garded as an abnormality, and the oblique position stands in his 

 generic diagnosis. Looss also states that the uterus passes between 

 the testes. On the basis of observations upon some 30 specimens of 

 Haplometra cylindrical Odhner (1911) maintains that the tandem 

 position of the testes must be regarded as normal for this genus, 

 and he points out emphatically that the uterus does not pass between 

 the testes but under them. That Odhner's observations are correct 

 is supported by a recent publication of Travassos (1930), who de- 

 scribes specific variations of Haplometra cylirhdrica. Odhner regards 

 Haplometra as related to, and derived from, Lepoderma (synonym of 

 Plagiorchis). He concludes that the modifications that Haplometra 

 exhibits follow as a natural result of its topography. He therefore 

 regards these features, which must be admitted as atypical for the 

 subfamily, as comprising a basis entirely adequate for the validity 

 of the genus. 



In Haplometrana intestinalis^ owing to the still greater diameter 

 of the testes as compared with the body width, a tandem and median 

 position of the testes becomes the only possibility. As a result of 

 this morphological feature, the passage of the uterus between the 

 testes is rendered a physical impossibility. Dorsoventral passage 

 of the uterus between the testes is a theoretical possibility but has 

 not been observed. The new generic concei^tion is based essentially 

 upon these facts. 



If Odhner's emended concept of the genus Haplometra is accepted, 

 Haplometrana is distinguished from Haplometra principally by the 

 possession of a definite seminal receptacle. Moreover, in Haplo- 



