THE OPALIXID CILIATE IXFUSORIA:NrS. 323 



Group 9 (fig. 247). 



P. fonnosae (p. 80) Bufo Formosa. 



P. quadiinucleata (p. 81) Bana Java. 



P. axonuoleata (p. 82) Bufo and Rana Eastern Asia. 



The species of this group are not very closely similar, but they 

 show in the three forms a progressive series in the multiplication of 

 the nuclei, which indicates the manner of origin of the genus Cepe- 

 dea from Protooimlina. We must regard these species as the most 

 highly evolved of the Protoopalinas, since they have passed beyond 

 the binucleateated condition. This group of species seems at first 

 sight to be of late Tertiary origin (fig. 237), being found in Java, 

 Formosa, and eastern Asia, but similar forms, becoming multi- 

 nucleated, must have evolved earlier, for their descendants, 

 Cepedca, show a distribution which necessitates an origin as early as 

 Jurassic times (see p. 325). Apparently transitional Protoopalinas, 

 with a tendency to become multinucleated, were present in the Ju- 

 rassic (fig. 233) in the India-Madagascar bridge and passed during 

 the late Tertiary to Asia-Malaysia (fig. 237). Their descendants, 

 Cepedea^ are in the Seychelles, Madagascar, Africa and South 

 America. But no Cepedeas and no Protoopalinas of Group 9 are in 

 Australasia. The transitional forms between the two genera have 

 persisted in Asia-Malaysia, but apparently their representatives in the 

 Ceylon-Madagascar-Africa bridge perished during the later Cre- 

 taceous when the bridge was broken up (fig. 235), but their de- 

 scendants, the Cepedeas, had already spread to Africa and South 

 America, where they are found to-day. It seems probable that trans- 

 itional species may be found in India when the Anura of this region 

 are searched for Opalinids, for it is apparently from India that 

 the Malaysian forms were derived. 



Ungnrouped Species. 



We have passed four species which do not fit into any of the 

 groups mentioned. Protoopalina ovoidea (p. 66) and P. xyster 

 (p. 67) from two Central American species of the genus G astro - 

 phryne^ while not very closely similar to each other, are both flat- 

 tened, P. xyster much so, and they indicate the probable manner 

 of origin of the genus Zelleriella from Protoopalina. Zelleriella, 

 as will be seen later, is in origin a southern South American genus, but 

 the only Imown transitional species between the genus Protoopalina 

 and the genus Zelleriella occur now in Central America and in species 

 of a family not represented in Patagonia at the time Zelleriella was 

 evolved there. To this interesting puzzle and its solution we will 

 return later (p. 369). 



Protoopalina saturnalis (p. 63), from the Mediterranean fish Box 

 loops., is a species with two sharply contrasted forms, one very 



