GENUS LICNOPHORA . 651 



above the termination of the ciliated pharynx ; endoplast elliptical, located 

 a little to one side of the same. Diameter of body 1-416". 



HAB. River water, infesting the interstices of the fresh-water sponge 

 Spongillafiiiviatilis. 



This species, described by Mr. N. H. J. Jackson in the ' Quarterly Journal of 

 Microscopical Science' for July 1875, was found by him infesting the outer or 

 cortical layer of examples of the fresh-water sponge Spongilla fluviatilis, taken from 

 the river Cherwell at Oxford, and were obtained by tearing up small fragments of this 

 organism under the microscope. Its motions from one portion of the sponge to the 

 other were observed to be very rapid, like those of Trichodina pediculus, it in the same 

 manner swimming with the adherent disc projecting forwards. The characteristic 

 external circlet of long spine-like setae are recognizable only when the animalcule is 

 at rest. The locomotive cilia fringing the periphery of the adherent disc were found, 

 under high magnification, to have a small bulbous enlargement at their point of 

 junction with the periphery. The presumed endoplast, with one exception invariably 

 present, took the form of an ovate, greenish, granular body, situated a little above the 

 centre of the ciliated pharynx. 



GENUS IV. LICNOPHORA, Claparede. 



Animalcules free-swimming or temporarily attached to a selected host, 

 highly elastic and changeable in shape, somewhat hourglass-shaped, having 

 an expanded, suctorial, posterior extremity or foot, a slender, flexible, more 

 or less compressed, stalk-like central region, and a dilated anterior body- 

 portion or capitulum ; the dilated capitulum obliquely flattened or concave 

 anteriorly, bearing a peristomal or adoral ciliary wreath, the left limb of which 

 is involute and descends into the oral fossa, the latter not followed by a 

 conspicuous ciliated pharynx ; the adherent posterior extremity enclosing 

 a delicate membranous ring, and bearing a single peripheral fringe of cilia. 



This genus has been instituted by Claparede* for the type originally described 

 by Cohn under the name of Trichodina Auerbachii, to which a second species has 

 been added by the first-named writer. Although at first sight the character of the 

 adhesive posterior extremity and the habits of the animalcule closely correspond with 

 those of the genus Trichodina and its allies, the structure of the peristomal region is 

 so distinct that Claparede regards it merely as a " mimetic " form of the latter, 

 requiring an independent family position. No details of the developmental pheno- 

 mena of either of the two known species have been as yet recorded, nor has the 

 presence of an endoplast or contractile vesicle been determined. The food-sub- 

 stances received at the oral aperture do not pass beyond the posterior border of the 

 capitulum. The parenchyma in both instances is exceedingly soft, rapidly breaking 

 up by diffluence when experimented on with reagents, or if subjected to abnormal 

 tension. 



Licnophora Auerbachii, Cohn sp. PL. XXXIII. FIG. 30. 



Body irregularly hourglass- or dumb-bell-shaped, the posterior adhesive 

 part having a raised rim or border, the pedicle-like central portion thickened 

 and compressed, the anterior capitulum ovate or pyriform, with an elongate, 

 somewhat harp-shaped fringe of large adoral cilia. Length 1-500" to 1-400". 



HAB. Salt water, occurring plentifully on the cuticular surface of the 

 Planarian Thysanozoon tuberculata: Naples (Claparede). 



* ' Annales des Sciences Naturelles,' torn, viii., 1867. 



