548 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



MONOUOTIIKIDM TERKBKANg Sp. IIOV. 

 [Plates 63, (34, 65; FijL,'8. 1 to 21.] 



. Body elongated, somewhat flattened, linear, slightly enlarged at the 

 extremities, which terminate in blnnt points, opaque, white. Head va- 

 riable, subsagittate, wedge-shape or bluntly rounded, a little broader 

 and thicker than the body, somewhat depressed dorso-ventrally but 

 without distinct bothria, translucent white with more delicate cuticle 

 than body. Posterior end of the body with irregular prominences 

 due to the development of ova in the uterus. Genital aperture ventral 

 about the posterior fifth ; testes in front of genital aperture occupy- 

 ing the greater jjart of the body; female genitalia behind the genital 

 aperture. Largest si)ecimen 28 mm. in length. Sometimes several 

 with heads buried in common pit in mucous membrane of host. 



Habitat: Intestine of Catostomus ardens, Heart Lake, Wyoming, July 

 28, 1890. 



Diesing makes this genus the type of his family Jlonobothria. The 

 genera included are CaryophyUcvus Gmelin, Moiiobothriiim Diesing, and 

 Diporus Diesing. These cestods are peculiar in that the body is not 

 segmented and contains but one set of genitalia. In other Avords a 

 single individual corresponds to one proglottis of an ordinary tape- 

 worm. The members of the group thus serve, in a measure, to connect 

 the cestods and trematods. 



Several large suckers which had been taken in a trammel net were 

 examined and about a dozen specimens of this parasite were obtained 

 from two of the fish. They were associated with Echinorhynchus tuber- 

 osns, and in each instance several of tbe individuals were found to be 

 attached to the intestinal wall with their heads buried in a common pit 

 in the mucous membrane. Some of these clusters were x^reserved 

 entire with a portion of the intestine. Upon examining the alcoholic 

 specimens one was found 7 mm. in length, which was wholly inclosed in 

 a pit in the mucous membrane. The walls of the pit were thick and 

 gristly and the head end of the parasite had nearly perforated the 

 intestinal wall. 



Tlie longest living specimen measured 28 mm.; as an alcoholic speci- 

 men it measured nearly the same, presenting the following dimensions 

 in millimeters: Length, 27; breadth, median, 2, expanding near anterior 

 end to 2.5, and near the posterior end tapering rather abruptly to 1; 

 thickness about 1, but increasing to 1.5 at the posterior end where there 

 are two or three moderately swollen or nodular jdaces. 



The following observations are based on alcoholic specimens: A 

 small specimen measured 17 mm. in length; median breadth, 25 mm.; 

 breadth near extremities, 2 mm. Tlie anterior end of this specimen was 

 sagittate and thicker than the body, posterior end bluntly tapering, 

 thicker than body, and somewhat swollen or nodular. Each end of the 



