285] NORTH AMERICAN MONOSTOMES 67 



MONOSTOMUM ORNATUM Leidy 1856 

 Syn. Monostomum ornatum Brandes 1892 

 Monostomum ornatum Braun 1893 

 Monostomum ornatum Diesing 1858 

 Monostomum ornatum Monticelli 1892 

 Monostomum ornatum Stafford 1902 



This species was described by Leidy as follows: 



"Body slightly compressed ovoidal, anteriorly broad; yellow variegated 

 with brownish red. Mouth infero-terminal, acetabuliform, transversely 

 oval. Penis conical, protruding a short distance below the mouth. Female 

 aperture a short distance below the penis. Length 1 to 1J^ lines, breadth 

 }/2 to % line, thickness J4 to J^ line." 



Habitat: Body cavity Host: Rana pipiens 



Locality: Philadelphia Collector: H. W. Warren 



Stafford (1902) questions the determination of these worms and con- 

 jectures that they belong either to the genus Haematoloechus sp. which 

 is commonly found in the lungs of frogs or to Dist. quietum or Cephalogoni- 

 mue amer. and have been liberated in the first case from the lung and in the 

 other cases from the small intestine of the host. He inclines to the former 

 view u on account of the ease with which the small ventral sucker may be 

 overlooked and the readiness with which worms may be freed from the lungs 

 without observation." He adds that, "it is unlikely to be Distomum quietum 

 from the position of the genital openings" and that "it could scarcely have 

 been Dist. retusum (Ceph. amer.?) since he reports it also in the same paper 

 although he does not describe it there but in an earlier number." 



In regard to the habitat of Monostomum ornatum Stafford says that "of 

 the hundreds of frogs I have examined I have never yet found a Trematode 

 free in the body cavity and I doubt if anybody else has ever obtained one 

 that did not first get there by the accidental cutting or tearing of some 

 other organ." 



The above assumption of Stafford that trematodes do not occur free in 

 the body cavity of frogs appears to be doubtfully correct. Osborn (1922) 

 and Cort (1913) report encysted Clinostomum in the body cavity. The 

 writer in examination of numbers of frogs has been able to observe these 

 and has several times found some of these worms out of their cysts and free 

 in the body cavity. These frogs were opened most carefully and worms 

 that might have been freed by the cutting of the body wall could not 

 have found their way to remote parts of the cavity in the time consumed 

 by the operation and examination. On the other hand it is hardly prob- 

 able that the dozen specimens recorded should escape from the lungs 

 unnoticed as suspected by Stafford and none be left to show the normal 

 habitat. However, as Stafford has noted and as was stated above, the worm 

 could scarcely have been Distomum retusum (Cephalogonimus americanus?) 



