50 



LEMBUS VELIFER Cohn, 



In 1898 I described Lemhiis ornatus ('98) as a new species. 

 Since then I have had this form quite frequently under observa- 

 tion, taken from the original locality (Lake Pontchartrain) and 

 recently from the Gulf. 



As a result of these further observations I have this to add to 

 my original description : It has two vibratile membranes — one on 

 each side of the oral furrow, the left one being striated and the 

 larger. When food is abundant, as in decaying infusions, the ani- 

 mal reaches its greatest size and the annulations tend to disap- 

 pear ; in many cases becoming entirely obliterated. 



Not infrequently, forms are met with containing two central 

 nuclei, presumably the beginning of fission. When well fed a 

 number of clear vacuoles often appear in the posterior half and 

 usually obscure the contractile vacuole. 



A careful examination of the descriptions and figures of the 

 five following forms has led me to conclude that they are one and 

 the same species seen under more or less varying conditions, and, 

 therefore, that the last four should be classed as synonymous with 

 Lemhtis velifcr Cohn. 



Lembus velifer Cohn %6. 



Lembus striatus Fabre-Domergue '85. 



Lembus intermedius Gourret & Roeser '86. 



Lembus ornatus Smith '98. 



Lembus infusiomim Calkins '02. 



Lembus elongatus C. & L. ('60) is, I think, too imperfectly 

 described for any consideration with the above group, although 

 Biitschli ('87) has placed L. velifer as synonymous with it. 



A review of the following features will explain my reasons for 

 the above conclusion. 



The variation in size is much less than holds for many other 

 ciliates and is, therefore, of no value ; the same may be said with 

 respect to the position of the oral aperture. 



All the authors agree in making special mention of the trans- 

 verse striae on the vibratile membrane, excepting Gourret & 

 Roeser ('86 L. intermedius) but who figure these striae very dis- 

 tinctly (PI. XXX, fig. 2, q. v.). 



The annulations are described and figured for L. velifer, inter- 

 medius and ornatus, figured, but not described for L. striatus and 

 absent in L. infusionum. The absence of the annulations in L. 

 infusionum may be explained, I think, by. one of my notes men- 

 tioned above. 



