THE H.EMOFLAGELLATES. 305 



si^ecies, they exhibit certain cytological differences, and T. karyozeukton 

 possesses one uncommon morjihological feature which well differentiates it. 

 It is, therefore, considered preferable to retain the distinctive names for 

 both, pending the further investigation of their exact degree of relation- 

 ship to T. rotatorium. 



T. mega, Button and Todd, 1903. Length from 82 — 87 jtt, the free ilagel- 

 lum being from 10 — 15 [i ; the breadth, in the widest part, is about 8/t. The 

 kinetonucleus is immediately in front of the trophonucleus, about one third 

 of the length from the anterior end. The longitudinal ridges and furrows 

 are well marked, but do not extend towards the anterior end of the body, as 

 in T. rotatorium (cf. fig. 58), becoming indistinct about opposite the 



Fig. 58. — T. mega, Button and Todd, t = trophonucleus. 

 X 1350. (After D. and T.) 



nucleus. Thus, while the posterior two thirds of the cytoplasm appears 

 composed of parallel, alternating darker and lighter bands, the anterior 

 third seems of a spongy and alveolar nature. 



T. karyozeukton, Dutt. and Todd, 1903. Length about 82'5 /^, that of 

 the free flagellum being about 15 M ; breadth G^/*. The cytoplasm (fig. 17 d) 

 shows the same general division into anterior and posterior portions which 

 characterises the last form. In this species, however, the kinetonucleus is 

 situated about midway between the trophonucleus ' and the proboscis-like 



' According to Button and Todd the trophonucleus itself is the pale, 

 structureless-looking body seen on the right in the figure, the large chromatic 

 grains in a compact mass being independent. It seems, however, equally 

 probable that the latter form an integral part of the nucleus, the pale 

 appearance being perhaps due to shrinkage. 



