GENUS LE UCOPHR YS. 587 



This form is distinguished from the preceding by its larger size, the greater pro- 

 portionate development of the peristome and more elongate and composite character 

 of the endoplast. Stein unites in this species both the Spirostomum ambiguutn and 

 5. virescetis of Perty. The author has obtained this species in great abundance in 

 pond water with Lemna trisuka near St. Heliers, Jersey, its comrades being 

 Urocentrum turbo, Parammcium chrysalis, and Spirillum voliitans ; the examples 

 then collected lived healthily for many weeks within the restricted limits of a wide- 

 mouthed bottle. Their long, filiform bodies, which exceed in length the dimensions 

 of any other Infusorial type, are quite conspicuous to the unassisted eye, and gleam 

 in the sunlight like golden threads. As shown in the accompanying figures, the 

 contractile vesicle in this animalcule is of very considerable relative size, its lower 

 extremity more particularly being often so greatly dilated as to occupy almost the 

 entire area of the posterior third of the body. 



The Spirostomum filum of Claparfede and Lachmann is regarded by Stein as 

 possessing insufficient characters for separate specific diagnosis. 



Genus IV. LEUCOPHRYS, Ehrenberg. 



Animalcules free-swimming, persistent in form, more or less oval or 

 egCT-shaped, the anterior extremity truncate ; pcristome-field confined to 

 the anterior third of the ventral surface, short, and widely harp-shaped ; oral 

 fossa continued into the interior of the body as a long, tubular pharynx ; 

 the outer or left border of the peristome alone bearing the fringe of adoral 

 cilia, no supplementary undulating membrane ; the peristome-field covered 

 with short cilia, similar to those which clothe the general surface of the 

 body ; endoplast band-like ; contractile vesicle and anal aperture postero- 

 tcrminal. Inhabiting fresh water. 



Leucophrys patula, Miill. sp. Pl. XXIX. Fig. 18. 



Body elongate-oval, compressed, somewhat kidney-shaped, one-half to 

 twice as long again as broad ; either transparent or coloured deep green 

 through the enclosure of chlorophyll-granules ; the two extremities slightly 

 curved towards the left, the anterior extremity truncate, the right-hand 

 corner of this frontal region angular, the opposite one rounded ; peristome- 

 field harp-shaped, equal in length to about one-quarter only of the entire 

 body ; oral aperture followed by a long tubular pharynx first produced 

 towards the right and then bent downwards and descending nearly to 

 the centre of the body ; endoplast band-like, convolute ; contractile vesicle 

 single, of large size, situated close to the posterior extremity, frequently 

 exhibiting two lateral prolongations which extend in a canal-like manner 

 up either side of the body. Length 1-120" to 1-72". 



Hab. — Fresh water. 



This species, s>Tionymous with the Trichoda patula of O. F. Miiller, and the 

 Spirostomum vircns and Leucophrys patula of Ehrenberg, has been the subject of 

 some contention among more modern investigators. Stein, regarding Ehrenberg's 

 Spirostomum virens as a morphologically distinct type, has conferred upon it the new 

 generic title of Climacostomum ; that of Leucophrys he retains only for a form which 

 he affirms to be identical with the Leucophrys patula originally figured by Ehrenberg 

 in the year 1830* and reproduced in part only in his greater work ' Die Infusions- 



* ' Abhand. Bed. Akad.,' S. 42 and 76, Taf. ii., figs. 1-6, 1830. 



