THE OPALINID CILIATE USTFUSORIANS. 



37 



one that I described in part 1. In a frog of the same species just examined, 

 however, I found neither of these present, but two different ones, both of 

 which seem to be new. Tliey are binucleated forms, and were present in great 

 numbers along with Nyctotherus cordiformis. The hirger of the two I propose 

 to call O. (1o7-salis. It is elongate in form and has a very broad anterior end, is 

 slightly flattenetl and swims along on either side, giving an occasional roll 

 over onto the other side as it progresses. This enables us to see a thin edge 

 which indicates that the animal is not circular in cross section, but broadly 

 oval. It is ciliated all over with very long cilia, and the two nuclei are always 

 situated in the anterior half of the animal. The most distinguishing feature 

 of the species is the greater width of the anterior end as compared with the 



Fig. 14. — Peotoopalina dorsalis. (After Raff.) 



posterior. It tapers gradually toward the hinder end and terminates in a 

 point. The cilia extend right to the posterior end. The average length is be- 

 tween 358ai and 430/i and at its widest portion it measures about 72fi. The one 

 drawn in the figure shows the characteristic cork-screwlike folds that the animal 

 presents when moving along. It also shows the slight turn of the " head " end 

 that is noticed during locomotion. 



The species at first sight resembles 0. intesiinalis slightly in outline and 

 position of the nuclei, but it differs from it in that the anterior end is broader 

 in proportion to the posterior, which tapers more and ends more sharply than 

 in O. intcstinalis, and in that the body is slightly flattened and so would not 

 be circular in cross section. 



PROTOOPALINA PERONII, new species. 



Type. — ^United States National Museum Cat. No. 16620. 

 Host. — Limnodynastes peronii (Dumeril and Bibron), one scant 

 infection from United States National Museum specimen No. 62748, 



Fig. 15. — Protoopalina peronii, X 460 diameters. 



from Wandandian, New South Wales, Australia, collected by C. M. 

 Hoy, August 1, 1919. Cleland and Johnston (1910) report finding 

 an unidentified species of ^^Opalina " [it might have been either a 

 Protoopalina or ZeUeriella, not an Opalina in our present termin- 

 ology] in this species of host. 



Measurements of an ordinary individual {fig. 15). — Length of 

 body 0.16 mm. : width of body at the wide anterior end 0.0326 mm. ; 



