Description of New Protozoa. 



33 



jelly. It then immediately proceeds to multiply itself in 

 geometrical proportion by fissure until masses are formed, 

 which, under favourable circumstances, attain a diameter of 

 three or four inches, and consist of aggregations of many 

 thousands of zooids. In this Protozoan the division is not 

 complete ; the zooids are united by fine threads, which permeate 

 the gelatinous mass, and are homologous with the stalks of 

 Epistylis. These threads also appear to have the property of 

 transmitting nervous impressions through the whole mass of 

 this compound animal, and rendering the movements of the 

 associated zooids consentaneous. 



When in England some years ago, I found in one of my 

 fresh-water aquariums a great number of specimens of Sten- 

 tor Miilleri, each one of which was surrounded at its base by 

 a flocculent deposit similar in structure to the lorica of Oph- 

 rydium versatile, and into which the animal could withdraw 

 itself. At first I considered that this state was the result of 

 disease, but further experience showed that the deposit was 

 never absent. Many of the animals inhabited a tall gelati- 

 nous pillar, by which they raised themselves considerably 

 above the surface on which they grew (fig. 11). Others by fis- 

 sure had formed colonies, which were attached to the glass, or 

 hung downwards while floating on the surface of the water ; 

 others, again, were swimming naked in search of sites for fu- 

 ture erections ; but no fixed animals were found to be destitute 

 of a lorica. I have repeatedly met with this animal since, 

 and always in the same loricated state. 



In the summer of 1857, a small species of Stentor, of a 

 deep chestnut colour, occurred in the pond of the Edinburgh 

 Botanical Gardens, which is in the habit of secreting a lorica 

 like that of Stentor Miilleri. This species, which I have 

 called castaneus, selects the tips of the shoots of Myriophyl- 

 lum for its abode, and glues all the opening leaflets together 

 with a mass of jelly, from which the zooids protrude their 

 wheel-bearing heads. The possession of a lorica removes 

 Stentores Miilleri and castaneus from the family Vorticellina 

 to that of Ophrydina, which (says Ehrenberg) " includes true 

 Vorticellse or Stentors inclosed in a gelatinous membranous 

 little box" or shell. In the last family, a new genus will 



VOL. II. e 



