390 ^Ir. T. Bentham on some 



towards that pole. Lip of acetabulum surrounded by two 

 distinct concentric circles, which lie closely together. Uncini 

 iS-iJO in number, and lying between the two outer concentric 

 circles and another circle which constitutes the edge of the 

 cytopharynx. The outer points of the uncini point in a 

 counter-clockwise direction. Edge of pharynx surrounded 

 by 30 cirri, and scattered over the whole of the oral surface 

 and placed irreguhirly are numbers of additional small cirri. 

 A distinct non-contractile vacuole is present on the aboral 

 projection, which part of the cytoplasm contains the food- 

 vacuoles. The rest of the cytophism is coarsely vacuolated 

 and contains no food-particles of any descrij)tion. Nucleus 

 extremely large, staining bright reddish-purple with Leish- 

 nian, and horseshoe-shaped. A distinct karyosome or 

 nucleolus is situated in the nucleus. In 50 °/q of cases the 

 nucleus appears to be absent (see below). 



The organism progresses by means of the aboral cilia, but 

 movement is chief!}' effected by a counter-clockwise rotary 

 motion, the oral surface being usually uppermost, liotatiou 

 is extremely rapid. When close to foreign bodies the 

 animal creej)S over the surface, after the manner of Euplotes 

 and Stylonychia. For this purpose it utilizes its minute 

 oral-surface cirri. Food in all cases was found to consist of 

 diatoms of the jS'avicella type and ingested Bacteria. 

 Ke])roduction is by binary fission, one individual retaining 

 the original cytopharynx, the other developing a new one. 

 Division is preceded by complete fragmentation of the nucleus, 

 wliich seemingly disajjpears entirely, appearing again in each 

 individual after actual division has taken place. Hence, as 

 mentioned above, a good many of the organisms ap[)areiitly 

 do not possess a nucleus. This organism, being closely 

 related to Ichthyophthirius, may be a factor in the dissemina- 

 tion of disease. 



The Infusorian was found later on the gills of Bhnnius 

 2)1tolis, but was absent from Centroiiotus guiineUus and (Jobius 

 ruthensparri. 



The figures of this genus given by Saville-Kent seem 

 totally inadequate as far as illustration goes. 



In conclusion, I may state that I have not appended any 

 new names to the parasites from Cottus and Raia, for tiie 

 simple reason that there is an enormous amount of confusion 

 centering round the genus Hcemogreganna. The procedure 

 of many authors is to give a new name to almost every 

 blood-parasite that they come across, whereas, within certain 

 classes, they are possibly merely dealing with different forms 



