GENUS LITONOTUS. 743 



surface of the body proper and tail-like region ; an even row of obliquely set 

 trichocysts bordering the entire left-hand margin of the neck ; contractile 

 vesicle single, situated towards the posterior extremity of the central body ; 

 endoplasts two in number, spherical, located a little in advance of the con- 

 tractile vesicle ; parenchyma of the central portion granulate and opaque, 

 that of the flattened neck and tail-like parts perfectly transparent. Length 

 of extended animalcule 1-75". HAB. Pond water, among Lemna. 



Wrzesniowski figures and describes this species under the title of Litonotus 

 folium, proposing to identify it with the Dileptus folium of Dujardin ; a reference 

 to the illustrations and diagnosis of that type as given by the last-named authority, 

 shows, however, that the two are perfectly distinct. In the present instance we have 

 an animalcule corresponding most closely in contour and in the extreme tenuity of 

 the elastic neck with the form already described under the title of Trachelocerca olor. 

 In the Dileptus folium of Dujardin there is no such extreme attenuation of the 

 anterior extremity, the granulation of the parenchyma is equally diffused from one 

 extremity of the animalcule to the other, and the cuticular surface is described as 

 nodular and presenting a reticulate aspect suggestive of the venation of a leaf, and 

 from which character it received its title. The relative dimensions of the two 

 animalcules are likewise very distinct, for while the length of Dileptus folium in its 

 normally extended state equals no more than six or seven times that of its greatest 

 diameter, the same proportions in the present species are as 12 or 13 to i. It 

 being clearly evident that the form now under notice cannot be held as synonymous 

 with Dujardin's type, it becomes necessary to find a substitute for the specific title 

 given by Wrzesniowski, and it is therefore proposed to confer upon it a name 

 associated with that of the able investigator to whom we are indebted for the true 

 interpretation of the structural characters of this interesting generic group. 



Litonotus fasciola, Ehr. sp. PL. XLII. FIGS. 5-11. 



Body linear-lanceolate, flexible but not contractile, from five to seven 

 times as long as broad ; the dorsal surface smooth and naked, the ventral 

 one longitudinally grooved or striate ; the neck-like portion scarcely equal- 

 ling in length one-half of the entire body, curved at its extremity towards 

 the right, gradually narrowing towards this region, and not sharply distin- 

 guished from the body by its greatly diminished diameter as in the preced- 

 ing species; the tail-like region short, obtusely pointed; oral aperture 

 situated towards the left and a little in advance of the centre of the body ; 

 the cilia clothing the under surface of the neck and in advance of the oral 

 aperture, of larger size than those on the remaining ventral surface ; 

 trichocysts obliquely set along the left-hand border of this region; con- 

 tractile vesicle single, situated near the base of the short, tail-like prolon- 

 gation ; endoplasts spheroidal, subcentral. Length 1-300" to 1-200". 



HAB. Pond water and vegetable infusions. 



This animalcule is identical with the Amphileptus fasciola of Ehrenberg and the 

 Loxophyllum amphileptus of Claparede and Lachmann. In concurrence with the 

 two last-named authorities, the author is inclined to regard the Dileptus folium of 

 Dujardin as likewise synonymous with this species, while the Amphileptus fasciola 

 of the same writer is apparently identical with one of the two forms next described. 

 Its reference to the Hypotrichous order under the generic title of Litonotus was 



