1 1)07.] XATUKAL SCIENCES OF PHILADELPHIA. 271 



Diiu/nostic characters. The small size aiul even tliameter, the con- 

 fluent, interconnected areolae, the prerloacal ridge and the absence 

 of hairs and spicules on the tail lobes afford a combination of characters 

 that seem to distinguish this from all previously described species. 



Distribution of the North American Species. 



In previous papers* I have described most of the species from the 

 continent of North America, and others have beea described by 

 Camerano^ and \'illot.^ The tenable species known from this region 

 are given below with their ranges, but it may be mentioned that 

 specimens have been collected in only three localities north of the 

 United States and from but a few in Central America, 



1. Paragordius varius (Leidy). 



This is the most abundant species in the United States. It is known 

 from Mexico, Lower California, and Guatemala; and in the United 

 States from Maine, New York, Massachusetts, New Jersey, Pennsyl- 

 vania, \'irginia. District of Columbia, Kansas, Texas, California, Illinois, 

 Micliigan, Arizona, South Dakota and New Mexico. 



2. Gordius villoti Rosa.* 



Mexico, Bay of Fundy, Ungava (Canada) ; and in the United States 

 from Maryland, Massachusetts, District of Columbia, New York, 

 PennsAdvania, Montana, Kansas, California, Michigan, Arkansas, 

 Vermont, Tennessee, Oklahoma, North Carolina, South Dakota, 

 Texas. It seems to be next abundant to the preceding. 



3. G. villoti difficilis (Montg.). 



North Carolina. This and the following may prove not to be tenable 

 but to be neotenic forms of G. villoti. 



4. G. lineatus Leidy. 



New York, Maryland, Pennsylvania, Michigan; most of the speci- 

 mens have been found in springs. 



' 1S9S, The Gordiacea of Certain American Collections, Bull. Mus. Comp. 

 Zool. Harvard, 32.— IH9S, Idem., II, Proc. California .\rad. Sci. (3), 1.— 1900, 

 Gordiacea from the Cope Collection, Biol. Bull., 1. — 1901, The Identity of the 

 Gordiacean Species, Chordodes morgani and C. puerilis, Proc. Acad. Nat. Sci. 

 Philadelphia. 



■ 1S9S, 1897, Monografia dei Gordii, Accad. Reals Sci. Torino. 



^ Monographie de.s Dragonneaux, 1874, Arch. Zool. gener. expcr., 3. 



* I would follow Camerano in dropping the name Gordius aquaticus Linn, on 

 account of insufficient diagnosis, and in adopting G. villoti Kosa for the species 

 described by Villot as G. aquaticus Linn. G. robustus Leidy, G. aquaticus robustus 

 (Leidy) ynihi, and G. aquaticus Linn, as pre\-iousIy used by me then become 

 svnonvms of G. I'illoti. 



