Pratoioa Punisttic in Fr(Mjs. 589 



anterior third of the body. They do not show the thread-like 

 structure connecting them which is shown in Metcalf's figure 

 (12), The chromatin material is gathered into masses around 

 the periphery of the nucleus. Ectosarc and endosarc are 

 clear!}' distinguished, but I have not been able to make out 

 any excretory organs (Fig. 6). Very small forms occur along 

 w'ltn these, and I think these represent the younger individuals 

 of the same species, for they seem to graduate up to the adults 

 in size. This species I have found in H. aurea, H. ewinyii and 

 Lim nodynasten dorsal is. 



Degeneration in these forms took place soon after they were 

 removed from the host. First of all the body gradually 

 altered its shape by the swelling up of the ectosarc and became 

 more and more spherical. After a while the ectosarc and 

 endosarc merged into one another and became indistinguish- 

 able. The cilia gradually ceased moving and ultimately the 

 body began to disintegrate and was attacked by countless 

 bacteria. 



Opalalina binucleata, n. sp. 



This is found in great numbers in Jjimnodynastes dorsalis, 

 and on one occasion I met with it in TAinnodynastes tasmatii- 

 eiixis. It is a broad, flat form with two nuclei, and is ciliated 

 equally all over its surface, the cilia being arranged in longi- 

 tudinal rows as in other Opalinae. It is broader and more 

 bluntly pointed at the posterior end than at the anterior 

 (Fig. 7) and moves along with the anterior end foremost. Its 

 usual position when swimming along, is on either flat surface, 

 but as it proceeds it occasionally rolls over from side to side. 

 The average length is 157 /< and the average breadth 100 fx, 

 but larger and smaller individuals have been met with. When 

 the animal turns over and presents itself edge on, it is seen 

 to be very thin as compared with its breadth (Fig. 8), and in 

 section would appear flat and oval. JNIelcalf (12) divides Opalinae 

 into the following groups: — 



(1) Species with two nuclei, l)odies circular in cross section. 



(2) Species with many nuclei, body circular or broadly oval 

 in cross section. 



