254 Prof. H. James-Clark on the Spongise ciliatse 



The mouth {m) is a very marked feature when contrasted 

 with that of other Flagellifers. It is usually to be observed in 

 a closed state (fig. 46, m), when it may be recognized as a 

 short, dark, sharply defined double line trending lengthwise 

 with the body, and situated on the ventral side, a short dis- 

 tance behind the base of the Jlagellum^ and just in front of the 

 contractile vesicle. When open, it has a more or less broad 

 oblong shape, and is more conspicuous than when closed. 

 During the introception of food, it is quite active ; but whether 

 for the purpose of mastication, or merely to manoeuvre the in- 

 coming particles, cannot be said positively, although it is pro- 

 bably with the latter design. The peculiar knobbed, parti- 

 coloured aspect of the body is due to the almost invariably 

 present large, highly refracting red and yellow granules in the 

 general cavity. 



The contractile vesicle (cv) is situated just behind the mouth, 

 but near the dorsal side of the body. At full diastole it is 

 globular, and its diameter is one-third of the breadth of the 

 region in which it is situated. The systole is abrupt, and 

 appears to be complete ; and the diastole is slow, seeming to 

 occupy all of the intervening time between the systoles. The 

 rate of systole was not ascertained with sufficient accuracy to 

 be recorded ; but I should judge it to be not more than four or 

 five times a minute. 



The reproductive organ is probably represented by a very 

 large, light, oval mass («) which nearly fills the middle of the 

 body. It has a decided outline, and, with the exception of a 

 rather large central nucleiform body, its contents are homo- 

 geneous. 



§ 13. Anisonema. 



imsonema concavum. 



nov. sp. PI. VII. figs. 65-69. 



Among all the heteronematous gubernaclifers, Anisonema 

 possesses the highest degree of differentiation in its flagella 

 iflj fi'^) '■> ^^^ whilst in Heteromita and Heteronema these organs 

 are comparatively more like each other, and arise from a nearly 

 common point, as in the Homoionemata, in the former genus 

 they exhibit a greater diversity of character, and also originate 

 from more widely separated regions. These are particularly 

 observable in the species before us now, and are certainly more 

 valuable diagnostic characters than the presence of an uncon- 

 tractile integument, by which to distinguish it from its con- 

 geners. The habitat of this animalcule is among tangled 

 masses of confervoid Algce in ponds and ditches, where decay- 

 ing substances are most abundant. Upon these it moves with 

 a more or less uneven pace, at one time gliding over a smooth 



