48 ILLINOIS BIOLOGICAL MONOGRAPHS [266 



The comparison of Arnsdorff with the figures and description of Stos- 

 sich for closely related species show a striking similarity to Cydocoelum 

 problematicum. Cydocoelum vicarium differs from this species, however, 

 in the relative size of the worms, the extent of the cirrus pouch and the 

 size of the eggs. 



Habitat: Intestine Host: Arquatella marilima mari- 



titna 

 Locality: North East Labrador Date: September 14, 1906 



Collector: Hantzsch Konigsberg Museum 



NOTOCOTYLIDAE Liihe 1909 



Of the monostome families which have up to this time been widely 

 studied no other family is of greater interest than the Notocotylidae. It 

 is in this family that the earliest records of the monostomes are found in 

 Catatropis verrucosa (Frolich 1789) collected from the rectum of Anas 

 domestica. These worms were classed by Frolich and Gmelin as Fasciola. 

 Ten years later Zeder (1800) removed them to the genus Monostoma. 

 They were later separated from the remaining monostomes by Diesing 

 (1839) and placed in a new genus Notocotylus which genus remains as the 

 type of the family. Although Diesing included this earliest known form in 

 his genus Notocotylus, it has been found in more recent time by Odhner 

 (1905) to be distinct from the Diesing type species, Notocotylus triserialis, 

 and was removed to the new genus Catatropis which place it holds at pre- 

 sent as type of that genus. A further study of Notocotylus triserialis Diesing 

 by Kossack (1911) revealed its identity with Monostomum attenuatum 

 Rud. 1809. Thus the species name becomes a synonym to Notocotylus 

 attenuatus. 



In regard to the early records of this family in America there still 

 remains a question. Some authors notably Barker and Laughlin would 

 place Monostomum affine Leidy 1858 as the earliest American record while 

 others doubt this determination and still others reserve opinion on the 

 matter. Barker (1916) questions the determination of Leidy and expresses 

 the opinion that Monostomum affine Leidy belongs to the genus Notocoty- 

 lus. While the description of Leidy (1858:110-112) is insufficient for an 

 accurate determination of the systematic position of this species certain 

 facts given in his description are distinct and seem sufficient to show that 

 this worm is not Notocotylid in character. The length of Monostomum 

 affine as given by Leidy is 6% lines or 13.5 mm which is two and one-half 

 to three times longer than any known species of this family. Likewise on 

 the same basis the Leidy species is at least three times wider than the 

 largest known Notocotylid. However, more important, intrinsic charac- 

 ters are the presence of a pharynx, an echinate penis and eggs prolonged at 

 one pole only. In addition these worms were taken from the gall-bladder 



