344 Janet W. Raff: 



very large numbers, and measured on an average 530/x long, 

 and 36yu, broad. They present a very attenuated or drawn-out 

 appearance, and exhibit the usual corkscrew-like motion (Plate 

 LXX., Fig. 1). The cilia are very long and of much the same 

 length all over the body {Plate LXX., Fig. 2), but at the anterior 

 end they are much more numerous and thickly arranged. Tlie 

 anterior nucleus is situated very near the front end of the body, 

 while the posterior one lies in about the middle of its length, or 

 slightly in the posterior half (Plate LXX., Fig. 1). In the younger 

 and shorter forms the position of the anterior nucleus varies, the 

 individual represented in Plate LXX., Fig. 2, having it situated fur- 

 ther down the body than is usual in the larger forms. This indi- 

 vidual measured 215/x in length. The smallest forms measured 

 lOO/x in length. 0. tenuis occurred along with 0. intestinalis 

 in Hyperolia marmorata, but in Crinia signifera it was the 

 only species of Opalina present. 



Opalina dorsalis, n. sp. 



The species of Opalina previously found in Limnodynastes 

 dorsalis are O. intestinalis and 0. hinucleata, the latter being a 

 new one that I described in Part L 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. They are 

 binucleated forms, and were present in great numbers along with 

 Nyctotherus cor di for mis. The larger of the two I propose to 

 call 0. dorsalis (Plate LXX , Fig. 3). It is elongate in form and 

 has a very broad anterior end, is slightly flattened, and swims 

 along on either side, giving an occasional roll over on to 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 Avidth of the anterior end as compared with the 

 posterior. It tapers gradually towards the hinder end and 

 terminates in a point. The cilia extend right to the posterior 

 end. The average length is between 358/x and 430/x, and at 

 its widest portion it measures about J'2/x. The one drawn in 



