289] NORTH AMERICAN POLY STOMID AE— STL' XKARD 



POLYSTOMIDAE 



HISTORICAL REVIEW OF THE FAMILY 



In 1758 Roesel von Rosenhof described and figured a "leech" from 

 the urinary bladder of the frog. This is regarded as identical with the 

 well known European parasite of the urinary bladder of the frog, 

 described by Frohlich (1791) as Linguatula integerrimum. M. Braun 

 (1792) described Planaria uncinulata from the urinary bladder of the 

 green water-frog and his description is so specific that there can be no 

 doubt that he had the same form described by Frohlich the previous 

 year. Zeder (1800) founded the genus Polystoma to contain the three 

 species, Linguatula integerrimum Frohlich which he rechristened Poly- 

 stoma- ranae, P. serration, and P. pinguicola. According to Stiles and 

 Hassall (1908) the type was clearly intended to be P. ranae = Planaria 

 uncinulata, and altho Braun had described the form correctly with the 

 suckers and hooks at the posterior end of the body, Zeder erroneously 

 stated in his characterization of the genus that the suckers were at the 

 anterior end. P. serration had been designated by Frohlich (1789) as 

 type of the genus Linguatula and P. pinguicola had been designated by 

 Treutler (1793) as type of the genus Hexathyridium. That Zeder was 

 in error in including these species in the genus Polystoma was demon- 

 strated by later studies. However Rudolphi (1809) retained them in the 

 genus Polystoma and listed three other species: P. taenoides Rud., P. 

 (hnticulatum, Rud., and P. venarum (Treutler 1793) Zeder 1803. 

 Among these species, it is probable that Treutler 's description was of an 

 artifact rather than a parasite, and the other two have been removed to 

 the Linguatulidae. 



Polystoma thynii was described from the gills of Scomber thynnus 

 by Delaroche (1811). Rudolphi (1819) renamed this species P. duplica- 

 tion and added a new species P. ocellatum from the throat of Emys 

 europa. This species is regarded as identical with that described by 

 Kuhl and Hassalt (1822) from the nasal cavity of Halichelys atra. P. 

 logiginis was described by delle Chiaje (1823) from Loligo vulgaris. 

 Blainville (1828) oriented the polystomes correctly and transferred P. 

 integerrimum, P. ocellatum, and P. thynii to a new genus Hexacotyle, 

 naming II. thynii as type. According to the rules of zoological nomen- 

 clature, however, the genus Polystoma must be retained. Kuhn (1829) 



