70 W. MILNE ON THE 



narrow, almost parallel. Toes sliort. Corona scarcely wider 

 than collar, sulcus narrow, upper lip triangular. There is a rect- 

 angular flap -like projection at the anus, which works as if on a 

 hinge. Size, l/90th inch. 



The upper lip of this species is most difficult to examine, as the 

 animal when feeding nearly always stands upright on its toes, and 

 whirls round and round on its vertical axis ; or swims about at 

 great speed. It is a very timid feeder when moored, the corona 

 is unfurled and almost instantly closed again, and this is repeated 

 again and again, so that the merest glimpse, of the upper lip is 

 had. The corona is scarcely wider than the collar ; the collar 

 rises high up, and the pedicels are very short, causing some 

 interference between the cilia of the primary and secondary 

 wreaths. The upper lip is of an uncommon shape for Philodina. 

 It is in shape a triangle extending as high as the discs, and lying 

 well back into the sulcus. The stoutest part of the animal is that 

 between the short, broad rostrum and the trunk — the dental seg- 

 ment is slightly the widest — and the trunk never gains the same 

 dimensions as the neck, until after heavy feeding. It is a rather 

 slow, deliberate creeper. The antenna is very long and generally 

 hangs backward, with the terminal segment bending over, and 

 when creeping gives a side view reminding one of that of a hare's 

 head with the ears laid back. Some species of the genus Rotifer 

 also have this appearance. Long setae are borne on the antenna, 

 which is thickest half-way between the base and the second seg- 

 ment, as if swollen there. 



There are brilliant eye-spots on the brain mass, well apart, 

 slightly elongated and set obliquely. The trunk is closely plicate. 

 Right from the trunk, the lumbar region and foot taper very 

 gently all the way to the spurs. 



Quite characteristic is a very peculiar process at the end of the 

 anal segment. It is a thin, almost membranous, rectangular 

 flap, somewhat bent in and over, on the top, so that the side view 

 is that of a hook. When the animal is stretched to the full, the 

 flap lies flat down, pointing forward over the contractile vesicle. 

 As the animal relaxes, it stands upright, and turns down in 

 the opposite direction when the foot is being planted. It almost 

 seems as if the flap worked on a hinge. It is of the same colour 

 as the foot, and thus easily overlooked. It was some time after 

 finding the animal that I noticed it first. 



