254 Prof. H. James-Clark on the Spongiz ciliate 
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 flagellum, 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 manceuvre 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 de tripe: by a very 
large, light, oval mass (7) 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. 
Anisonema concavum, nov. sp. Pl. VII. figs. 65-69. 
Among all the heteronematous gubernaclifers, Anisonema 
possesses the highest degree of differentiation in its flagella 
(ft, fl’) ; for whilst in Heteromita and Heteronema these organs 
are comparatively more like each other, and arise from a nearly 
common point, as in the Homotonemata, 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 yncon- 
tractile integument, by which to distinguish it from its con- 
geners. The habitat of this animalcule is among tangled 
masses of confervoid Algw 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 
