GENUS LEMB US. 547 



the body, numerous long vibratile cilia enclosed within the hood-like 

 membrane; cuticular cilia setose; endoplasm usually enclosing green 

 granules. Length 1-840" to 1-650". HAB. Fresh water, among Chara. 



The presence of an undulating membrane at the anterior extremity, correspond- 

 ing closely with that of Pleuronema, while suspected by Perty, is more conclusively 

 demonstrated by the figures and description of Fresenius,* from which the accom- 

 panying illustration is derived. According to the two authorities quoted, it swims 

 through the water, revolving on its long axis, creeps slowly, or springs from one 

 side to the other after the manner of Cyclidium, aided, apparently, under the last 

 conditions, by its setose cuticular cilia. Multiplication by transverse fission is 

 reported by its original discoverer. 



Fam. XI. LEMBIDJE, S. K. 



Animalcules free-swimming, elongate or vermicular, ciliate throughout, 

 oral and cuticular cilia diverse in character; oral aperture ventral, asso- 

 ciated with a prolonged crest-like membranous border. 



The members of this very natural family group are characterized by the peculiar 

 crest- or sail-like contour of their supplementary adoral membranes. As yet but two 

 generic forms, Lembus and Proboscella, can be included in it. Both represent the 

 fruits of the most recent investigation. 



GENUS I. LEMBUS, Cohn. 



Animalcules free-swimming, elongate - clavate or vermicular, highly 

 elastic ; oral aperture ventral, subcentral, an extensile, subtriangular or 

 band-like, undulating membrane produced along a furrow on the ventral 

 surface, which extends from the anterior extremity backwards to the oral 

 aperture, cilia of larger size than those of the cuticular surface usually 

 developed along its inner border ; contractile vesicle conspicuous, posteriorly 

 located. Inhabiting salt water. 



With reference to the peculiar modification of its characteristic undulating mem- 

 brane, the genus Lembus occupies among the Holotrichous Infusoria a position 

 corresponding to that held by Condylostoma and Blepharisma with relation to the 

 higher Heterotricha. Three species are now added to the type form introduced by 

 Cohn. 



Lembus velifer, Cohn. PL. XXVII. FIGS. 62 AND 63. 



Body elongate, lanceolate or clavate, from five to eight or ten times as 

 long as broad ; undulating membrane and adoral furrow commencing at a 

 short distance from the anterior extremity, extending backwards through 

 two-thirds of the length of the entire body, this portion of the body narrow 

 and linear, the posterior third cylindrical, more or less rounded posteriorly. 

 Adoral cilia long and fine, produced beyond the outer border of the undu- . 

 lating membrane; cilia of the cuticular surface rather longer towards the 

 anterior extremity ; surface of the posterior half of the body finely annulate 

 transversely; contractile vesicle posteriorly located. Length 1-480" to 

 1-240". 



* ' Beitrage zur Kenntniss Mikroskopischer Organismen,' Frankfurt, 1858. 



