452 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



of animals is now materially reduced, or that the trematodes of these 

 regions are chiefly derived from (or ancestral to) relatives not yet generi- 

 cally differentiated. 



In addition to new species and genera, the following taxonomic 

 changes are proposed in this paper: (1) Prosorhynchus caudovatus, n. 

 nom. is proposed for the P. crucibulus of Eckmann, 1932. (2) Doll- 

 fustrema Eckmann, 1932 is considered a synonym of Mordvilkovia 

 Pigulewsky, 1931. (3) Pseudoprosorhynchus Yamaguti, 1938 is con- 

 sidered a synonym of Neidhartia Nagaty, 1937. (4) Bucephalus various, 

 n. nom. is proposed for the B. polymorphus of Nagaty, 1937. (5) Buceph- 

 alus kathetostomae (Manter), n. comb, is proposed for Rhipidocotyle 

 kathetostomae Manter, 1934. (6) Hypocreadium Ozaki, 1936 is con- 

 sidered a synonym of Pseudocreadium Layman, 1930 and P. patellare 

 (Yamaguti, 1938) is a n. comb. (7) Proctotrema truncata (Linton), 

 n. comb, is proposed for Genolopa truncata Linton, 1910. (8) Theledera 

 Linton, 1910 and Cithara MacCallum, 1917 are considered synonyms of 

 Tergestia Stoss., thus resulting in Tergestia pectinata (Linton), n. comb, 

 and T. priacanthi (MacCallum), n. comb. (9) Parahemturus parahemi- 

 urus Vaz and Pereira, 1930, P. platichthys Lloyd, 1939; P. atherinae 

 Yamaguti, 1938, P. harengulae Yamaguti, 1938 all are considered to be 

 synonyms of P. merus (Linton, 1910). (10) Gonocercella atlantica, new 

 species is named for "Dist. sp." of Linton, 1905, p. 367, fig. 204. (11) 

 Siphoderinae Manter, 1934, Neochasminae Van Cleave and Mueller, 

 1932, and Exorchiinae Yamaguti, 1938 all are considered synonyms of 

 Heterophyinae Ciurea, 1924. 



Twenty-three species (more than 25 per cent of the total number 

 collected) are known from the American Atlantic. These 23 species 

 are: Bucephalus varicus, Derogenes varicus, Dinurus harbatus, D. lon- 

 gisinus, Haynacreadium mutahile, H. oscitans, Haplosplanchnus acutus, 

 H. pomacentri, Helicometra fasciata, H. torta, Helicometrina nimia, 

 Hirudinella beebei, H. clavata, Lecithochirtum microstomum, Lepidape- 

 don nicolli, Lepocreadium bimarinum, Parahetniurus merus, Proctotrema 

 longicaecum, Prosorhynchus ozakii, Stephanostomum casum, S. mega- 

 cephalum, Sterrhurus fusiformis, Tergestia laticollis. Six species have 

 been previously reported from Japanese or Siberian seas. These are: 

 Cymbephallus carangi, Opechona inimici, O. orientalis, Opegaster para- 

 pristipomatis, Prosorhynchus aculeatus, Stephanostomum hispidum. A 

 single species, Helicometra sinuata, is known elsewhere (to date) only 

 from European waters. 



