196 Dr. R. Greef on the Structure and 



the latter than on the former ; wings purplish brown ; feet 

 reddish brown. 



Total length 2| inches ; bill f, wing If, tail 1^, tarsi -^. 



Habitat. Citado and Pallatanga, in Ecuador. 



Remark. Except in being of much smaller size, this little 

 species is very like the black- and stout-billed Ghlorostilhon 

 melanorhyncha, which, in my ' Introduction to the Trochilidas,' 

 I have, as I now believe, erroneously placed as synonymous 

 with C. chrysogaster^ a bird inhabiting countries further north 

 than Ecuador, The C. pumilus is also very nearly allied to 

 the C. assimilis of Lawrence, but differs from that species in 

 being still smaller, and in having a shorter and less deeply 

 forked tail. 



XXII. — Investigations upon the Structure and Natural History 

 of the Vorticellse. By Dr. Eichard Greef. 



[Continued from p. 112.] 



External Hahit of the Vorticellse. 



In general terms the external form of the individual Vorti- 

 eellan animals may be described as cup-, urn-, or bell-shaped, 

 to which latter, as the most suitable conception, the whole 

 group is indebted for the name of bell-animalcules [Ghcken- 

 thierchen) conferred upon it by Ehrenberg, and for the cognate 

 denominations of tree-bells {Carchesium) ^ column-bells [Epi- 

 stylis), operculum -bells {Opercularia) , double-bells [Zootham- 

 nium)^ &c. According to former notions this denomination 

 would be still more suitable, since, as is shown by nearly all 

 the older descriptions and figures, it was supposed that the 

 animals were hollowed like bells or cups, and furnished with 

 cilia only on their free margin. Subsequent observations, 

 however (first made by Ehrenberg), showed that the anterior 

 mouth of the bell was closed by a more or less circular disk 

 clothed with cilia, and that it was only behind this disk that a 

 canal led, through a lateral buccal orifice, into the body of the 

 bell, which was filled with contents, i. e. solid. 



The anterior ciliated disk, or the rotatory organ, is exter- 

 nally surrounded by a broad, membranous seam, the so-called 

 peristome. When the rotatory organ expands, the peristome 

 becomes reverted, like a cushion, and is then surmounted by the 

 extruded ciliated disk, which is frequently upon a short neck, 

 and at the same time separated from it by a furrow (PI. XIII. 

 figs. 2, 6, &c.). This separation, however, occurs more or 

 less distinctly in the different species ; nay, it may be almost 

 entirely wanting, as for example in Epistylis jiavicans, in which 

 the ciliated disk appears to pass directly and without any 



