Protozoa Pai-asiflc In Froy^. 587 



rally speaking the Opalinae are in greater numbers. Only 

 very rarely are they ever completely absent, and then it seems 

 to be owing to the lack of food material in the intestine. 

 Taking the Nyctotherus first, the following is an account of the 

 species represented in the large intestine. 



Nyctotherus CordlfOPmis, Ehrenberg. 



This measures on an average 213/ax128^, but larger and 

 smaller specimens are also present. In three of the species of 

 frog examined — viz. : H. aurea, U. ewingii and H. tasmani- 

 ensis a very large form of Nyctotherus is present, sometimes, 

 but rarely, in great numbers. This I take to be the same 

 species, but of an abnormally large size, measuring on an 

 average 398 fx long and 255 /x broad, and appearing quite 

 giant in size as compared with the others (Fig. 4). Figure 5 

 shows one of these with a small individual inside it which thus 

 enables us to see how very much they differ in size. I might 

 here mention that individuals of extreme size as compared 

 with the normal have been observed in other groups of the 

 Protozoa. Thus Dobell (4) records the presence in Tricho- 

 mastix serpentis of giant forms when he says : " An individual, 

 instead of dividing when it reached a certain size, continued 

 to gi-ow. In this way giant individuals arose which reached 

 the enormous length of 30 /i, i.e., about twice the normal 

 length." These, however, were involution forms which were 

 produced through overfeeding, whilst my remarkably large 

 forms are present in the intestine living under normal condi- 

 tions. They may, however, have been produced in much the 

 saxne way by over-feeding. 



A peculiar structure visible in some of the normal specimens 

 stained in Heidenhain's iron haematoxylin is a backwardly 

 directed flagellum (Fig. 2) running down from the posterior 

 end of the oral groove and then curving forwards towards tho 

 entrance to the cytopharynx. This is very definite in these 

 preparations but does not show up with other stains. I can 

 find no reference concerning it anywhere, unless I regard 

 Saville-Kent's long, stiff and outwardly projecting seta of this 



