Infusoria of the Island of Bombay. 259 



almost spherical, and confined to the centre. In fig. 18 the 

 whole form is spicular, and in iig. 19 also spicular, but bifid 

 at one extremity. Fig. 20 represents a sigmoid form ; and all 

 appear to me to be derived from fig. 22, which is the active 

 form of the Chlamydococcus that was in company with them. 



No difficulty, however, can arise from my having made for 

 the time being a separate genus for this hybrid organism, 

 since, if hereafter it should be proved to be merely a sportive 

 form of Chlamydococcus , the generic name can be erased, and 

 the specific one alone retained for the variety. Meanwhile 

 the record as it is may not be without its advantages in the 

 history of this cell. 



H ALTER! A, Duj. 



Halteria pulex , Clap, et Lachm. PI. XVII. fig. 23. 



This infusorium, described and figured by the eminent au- 

 thors of the ' Etudes sur les Infusoires ' (p. 370, pi. 13. figs. 10, 

 11), has always attracted my attention, from its being so ex- 

 quisitely sensitive (I might almost say timid), in combination 

 with its extreme minuteness — since the instant it comes in 

 contact with another animalcule, it leaps backwards, with the 

 appearance almost of instinctive fear, although it is hardly 

 one-thousandth of an inch long, and less than this in breadth. 

 Its body is globular, surmounted by a neck, which is inflated 

 below (where it joins the body) by the presence of two actively 

 contracting vesicles (c c), beneath which, again, is a frill of 

 straight radiating cilia, arising from the constriction which 

 marks the union of the neck with the body (a). In front the 

 neck is truncated, supporting several short parallel straight 

 cilia arranged brush-like — that is, all of one length, like the 

 so-called teeth in Chilodon (b). I could see no nucleus ; and 

 both the body and neck were charged with transparent cor- 

 puscles reflecting a yellow-greenish light. Size, l-1080th inch 

 long (including teeth-like cilia) by 1 -1800th broad. 



Hab. Island of Bombay ; freshwater tanks. Progression 

 rapid, rotatory, produced by a spinning motion of the frill of 

 cilia, which can also be used as legs for creeping ; leaping 

 here and there, especially backwards, when coming in contact 

 with another animalcule. Anterior part of the neck and tooth- 

 like cilia retractile. 



Obs. The infusorium described and figured by the authors 

 above mentioned as existing in salt water would hardly merit 

 further mention, had I not often found it also in the fresh- 

 water tanks of the island of Bombay, and with two contract- 

 ing vesicles, which these authors had not seen. Like these 

 naturalists, however, I was not able to discover the nucleus. 



