Protozoa from Fishes, 389 



rounded and tlie other pointed (see PI. XVII. fig. 2, 4). Tlie 

 nucleus was, as a rule, centrally placed, large, and compact. 

 No forms were peon with a diffuse nucleus. A number of 

 granules of volutin were present scattered about the cell- 

 body, and usually two of these grains were larger than the 

 rest and wore present at the more pointed end of the parasite 

 (see PI. XYIl. fig. 2, 1 &^). A distinct vacuolar space was 

 sometimes present at the pointed end of the body, and was 

 always close to the two organella! above-mentioned. The 

 capsule at both ends of the parasite was slightly thickened, 

 but its edges were never evident. In a few instances two 

 parasites were seen together in a single erythrocyte. Tliese 

 always lay parallel to one another, and were never far apart. 

 In this character the parasite was very similar to Ilwmo- 

 greqarina higemina, found in blennies, and no distinct 

 difference could be discerned. 



Infusoeia. 



While examining the blood of Co^^m5 scorpius for parasites, 

 an infusorian of the genus of Trichodina (Ehrenberg) was 

 discovered on the gill-rakers. A blood-smear had been made 

 from one of the gills and w^as stained with Leishman. On 

 examination, the smear was found to contain numerous 

 members of the above genus. The organism is closely 

 related to T. scorpccna found on Scorpcena and Trigla, but 

 differs markedly from that species in shape, size, and iu the 

 characters and disposition of the acetabulum. 



Description of Organism. (See PI. XYI. fig. 3.) 



Shape a flattened cylinder, having a small conical projec- 

 tion on the aboral surface. Size about 80 /x across the oral 

 disc, but varying within certain limits. The aboral surface 

 also measures 80 /a in diameter. The thickness of the 

 organism is about 50 fi, but this measurement varies slightly 

 with the movement of the cytoplasm, although the shaj)e of 

 the cell-body is almost fixed. Diameter of acetabulum to its 

 outer ring 30 yx. There is a strong band of oral cilia round 

 the edge of tl;e concave ventral surface, and running from 

 the upper to the lower surfaces and destroying the complete 

 contour of the cylinder, is a distinct wide and deep groove 

 representing the anus. There are no aboral cilia, those of 

 the oral contour, however, running down into the cyto- 

 pharynx. Acetabulum much smaller than in T. scorpama, 

 about half as broad as long, and in optical section curved 

 towards the oral pole, the concavity of the ring pointing 



