219] TURBELLARIA FROM THE MISSISSIPPI BASIN- HIGLEY 25 



position, was visible to the naked eye. Thus the intestinal anatomy is con- 

 spicuous in a way unknown among other planaria. The structure as a whole 

 is especially well defined and all the parts easily distinguishable. 



Family Catenulidae 



The family CatenuUdae was created by von GrafF in 1905 to contain five 

 genera, two of which, Stenostoma O. Schm. and Alaurina W. Busch, had, up 

 to that time, been grouped under the family name Stenostomidea, and a third, 

 Microstoma O. Schm. had belonged to the Microstomida. To these three, he 

 added two others, Rh3mchoscolex Leidy and the old Catenula Anton Duges, 

 which had hitherto been grouped by itself, seemingly unrelated. He took the 

 name of the new family from the oldest genus. Two years later, in 1907, Alex. 

 Luther added the genus Lophorhynchus, a species with very heavy pre-oral 

 furrow. Then, on the basis of the paired excretory tubules, and in agreement 

 with the researches of Vejdovsky (1882), Sekera (1883) and himself, he removed 

 Microstoma and Alauria, putting them together to form the Microstominae, a 

 sub-family of the Macrostomidae. Another change came in 1908, when von 

 Graff substituted the generic name Fuhrmannia for Lophorhynchus, since the 

 latter was already in use. The list of genera belonging to the Catenuhdae was 

 thus 1) Catenula, 2) Fuhrmannia, 3) Stenostoma, 4) Rhynchoscolex, and 

 this classification now stands. 



This family is the simplest of the rhabdocoel group. It is characterized by 

 the lack of an anterior prolongation of the intestinal cavity, and by the posses- 

 sion of a single protonephridium. The testes and ovary are always unpaired, 

 tho in general they are not to be found since periods of sexual maturity are 

 rare. The common method of reproduction is by budding and chains of two, 

 four, or six zooids are much more frequent than single individuals. Without 

 eyes or rhabdites, almost entirely lacking in color, these forms are most in- 

 conspicuous. With good reason, have they been likened to large protozoans, 

 and superficially, at least, seem to be entirely without specialized structure; 

 they are always small, few in number, and compared with other types easily 

 overlooked. 



Of the four genera, three have been reported from this country. Many 

 years ago one species of Catenula and two of Rhynchoscolex were collected 

 in small numbers around Philadelphia. They are probably present in other 

 places in the eastern states, but have not yet been found west. The genus Sten- 

 ostoma is quite different in its distribution. Several species have been de- 

 scribed from very separated locahties and the genus as a whole seems to have 

 a rather wide-spread occurrence. It was first described by O. Schmidt (1888), 

 who recognized the characters which separate it from Microstoma. He named 

 two species and during the next thirty years eight others were added by 

 different investigators. Up to 1905 the genus name was Stenostoma, then it 

 was changed to Stenostomum, without adequate reason, I think. In the 

 United States, two European species have been identified, while four new ones 



