291] XORTH AMERICAX rOLYSTOMIDAE—STUSKARD 11 



groups Tristomeae and Polystomeae, which he regarded as families 

 Under the Polystomeae as subfamilies he listed Polystomidae, Octoboth- 

 ridae ( = Oetocotylidae), Gyrodaetylidae, and the new subfamily Micro- 

 eotylidae ; the latter including Microcotyle, Axiue, Gastrocotyle and the 

 entirely unlike genera, Aspidogaster, Cotylaspis and Aspidoeotyle. To 

 the Polystomidae he added the genera Onchocotyle and Diplobothriura, 

 and in the genus Polystoma included the two species P. intcgcrriinum 

 and P. occllaium. 



In regard to the previously mentioned forms St. Remy (1891) fol- 

 lowed the famih' and subfamily divisions of Taschenberg, tho adding 

 new genera to each of the subfamilies and removing Aspidogaster, Coty- 

 laspis, and Aspidoeotyle from the Microcotylidae. To the Polystomidae, 

 Wright and Maeallum had added the genus Sphyrauura, and in the genus 

 Polystoma were listed the new species P. oblongum Wriglit and P. coro- 

 nafum Leidj'. 



Increased knowledge of the trematodes disclosed so many exceptions 

 to their classification according to life history that Monticelli (1892) 

 proposed a new arrangement of the group, based on morphological char- 

 acters. To contain the forms previously classed as Monogenea, he pro- 

 posed the suborder Heterocotylea. He raised the Monocotylidae and 

 Gyrodaetylidae from subfamily to family rank, making five families in 

 the Heterocotylea. In the family Polystomidae he retained the sub- 

 families Polystominae, Oetoeotyliuae, and Microeotylinae of former 

 authors. 



So far as the Polystomidae are concerned, the synopsis of Pratt 

 (1900) does not differ from that of St. Remy and Monticelli. 



Later Monticelli (1903) worked out a new classification of the 

 Heterocotylea, separating the forms on the basis of differences in the ad- 

 hesive apparatus. He an-anged the families in two tribes, Oligocotylea 

 and Polj'cotylea, the former containing the forms with few suckers and 

 the latter those with many suckers. This division he says is not of great 

 systematic importance but may be of practical value in the identiiicatiou 

 of families. In the Oligocotylea he included the families Tristomidae, 

 Slonocotylidae, Udonellidae, Calceostomidae, Gyrodaetylidae, and Dico- 

 tylidae ; and in the Polycotylea the families Polystomidae, Oetocotylidae, 

 Hexacotylidae, Platycotylidae, Pleurocotylidae, and Microcotylidae. 

 Among these the Udonellidae, Oetocotylidae, and Microcotylidae are 

 raised from subfamily to family rank, and the Calceostomidae, Dicoty- 

 lidae, Hexacotylidae, Platycotylidae, and Pleurocotylidae are new fam- 

 ilies. The family Polystomidae contained the single genus Polystoma 

 with the species P. integerrhnum, P. occllutuin, P. oblongum, P. coro- 

 natum, and P. hassalli. 



