291] NORTH AMERICAN POLYSTOMIDAE—STUNKARD 11 



groups Tristomeae and Polystomeae, which he I'egarded as families 

 Under the Polystomeae as subfamilies he listed Polystomidae, Octoboth- 

 ridae ( = Octocotylidae), Gyrodactylidae, and the new subfamily Miero- 

 cotylidae ; the latter including Microcotyle, Axine, Gastrocotyle and the 

 entirely unlike genera, Aspidogaster, Cotylaspis and Aspidocotyle. To 

 the Polj'stomidae he added the genera Onehocotj'le and Diplobothrium, 

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

 and P. ocellatum. 



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

 lowed the family and subfamily divisions of Taschenberg, tho adding 

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

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

 Wright and Macallum had added the genus Sphyranura, and in the genus 

 Polystoma were listed the new species P. dbloagum Wright and P. coro- 

 natum Leidy. 



Increased knowledge of the trematodes disclosed so many exceptions 

 to their classification according to life history that Montieelli (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 

 Gyrodactylidae from subfamily to family rank, making five families in 

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

 families Polystominae, Oetocotylinae, and Mierocotylinae of former 

 authors. 



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

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



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

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

 hesive apparatus. He arranged 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 identification 

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

 Monocotylidae, Udonellidae, Calceostomidae, Gyrodactylidae, and Dieo- 

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

 Hexacotylidae, Platycotylidae, Pleurocotylidae, and Microcotylidae. 

 Among these the Udonellidae, Octocotylidae, and Microcotylidae are 

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

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

 ilies. The family Polystomidae contained the single genus Polystoma 

 with the species P. integerrimum, P. ocellatum, P. oblongum, P. coro- 

 natum, and P. hassalli. 



