THE OPALINID CILIATE IXFUSORIAXS. 



185 



Measurenients: A, of a large individual; B, of a small individual; 

 C, of a plicate form — 



Measurements. 



mm. 

 0.325 

 .085 



mm. 

 0. 0865 

 .05 



Leugtli of body 



Wid"th of body 



Thickness of body: 



Anterior.....' .013 .008 



Middle .014 .013 



Posterior .0125 .016 



Diameter of nucleus 0. 004- . 0048 0. 00675- . 0076 



Cilia Line interval: 



Anterior .00187 .00118 



Posterior .0033 .00275 



0.1 

 .076 



0. 005- . 0062 



Fig. 154. — Opalina obtrigoxoidea, fro.m Raxa 

 palustris, showing some individuals of the 

 form plicata, x 117 diameters. 



OPAUNA OBTRIGONOIDEA, form PLICATA, new forma. 



T7/pe. — United States National Museum Cat, No. 16562. 



Hosts. — Ba)ia palustris LeConte, type infection. Woods Hole, 

 Massachusetts, July 17, 1919; M. M. Metcalf, collector; also Bufo 

 fou'leri Putnam, from the 

 same locality, summer 1919: 

 M, M. Metcalf, collector ; and 

 another infection in this same 

 host from Mount Monadnock. 

 XeAv Hampshire, August, 

 1912, M. J. Rathbun. 



In some infections of Opa- 

 lina ohtHgonoidea we find 

 many individuals which are throAvn into longitudinal folds or ridges 

 giving a quite distinctive appearance. A simihir longitudinal plica- 

 tion is common in some other American Opalinas. I have not ob- 

 served it in Opalina ohfrigona in Europe. 



OPALINA, species (?). 



A specimen has been deposited with the United States National 

 Museum as No. 16556. 



Host. — Rana septentrionalis Baird, one scant infection, from 

 United States National Museum specimen No. 13622, 45 mm. long, 

 from Lucknow, Ontario, 1883 ; J. H. Garnier, collector. 



Measurements of a large hidivldAial. — Length of body 0.23 mm. ; 

 width of body 0.0456 mm. ; diameter of nucleus 0.004 mm. to 0.005 

 mm. 



These forms resemble 0. ohtrigonoidea from Rana jnpiens., but are 

 too poorly preserved for description and classification. 



OPALINA OBTRIGONOIDEA AMERICANA, new subspecies. 



Type. — United States National Museum Cat. No. 16537. 

 83103—23 13 



