66 ILLINOIS BIOLOGICAL MONOGRAPHS [284 



Species Inquirendae 

 CLINOSTOMUM (?) INCOMMODUM (Leidy) 



Syn: Monostotnum incommodum Leidy 1856 

 Distoma oricola Leidy 1884 

 Distotnutn incommodum Leidy 1890 

 Monostomum incommodum Leidy 1904 



Monostomum incommodum is described by Leidy as follows: "Body 

 compressed, above convex, below concave, sides parallel anteriorly convex, 

 posteriorly angularly convex. Head continuous with the body, obliquely 

 truncated. Mouth round, surrounded with a wide circular lip which is 

 emarginate below. Male generative aperature? communicating with a 

 hemispherical cavity (acetabulum?) one-fourth the length of the body from 

 the head. Length 9 lines, breadth V/2 lines. 



Habitat: Fauces Host: Alligator mississippiensis 



Locality: Florida Collector: J. W. Bailey 



Date: Previous to 1856 

 Leidy (1890) places this species as Distomum incommodum and as a 

 synonym of this species his Distoma oricola from the mouth of Alligator 

 mississippiensis. On the basis of the later determination of Leidy (1890) 

 his description of Distoma oricola is here included for the purpose of com- 

 parison and as evidence for the disposition of Monostomum incommodum. 



Distoma oricola Leidy 1884 



"Body elongated elliptical, moderately wider and thicker posteriorly and 

 ending in a blunt, angular extremity, convex dorsally and flat ventrally, 

 unarmed, smooth or minutely wrinkled transversely. Mouth subterminal, 

 and enclosed with a reniform lip succeeded by a linear annulus. Acetabu- 

 lum large, globular, included at the anterior fourth of the body, and open- 

 ing ventrally by a conspicuous central aperature. Generative orifice 

 ventral, at the posterior fourth of the body. Length, 15 to 20 mm; breadth, 

 3 mm. Eight specimens obtained from the mouth of the alligator, A. 

 mississippiensis, in Florida, by Mr. Stuart Wood." 



Pratt (1902) surmises that this species is allied to the genus Clinosto- 

 mum. This view is supported by Ward (1918). Then if, according to this 

 view the determination of Leidy, that Distoma oricola is a synonym of 

 Monostomum incommodum which he determined later (1890) as a Distome, 

 Distomum incommodum, be accepted, Monostomum incommodum is like- 

 wise allied to the genus Clinostomum. 



