_ asbelonging to the shortened type. The 
: in which i 
: vhs Posterior portion, in the shortened form it is parali y 
a I was not able to detect in the shortened a the 
cona Contractile vesicle, situated posteriorly, was anpi tho- 
h 3 a anterior vesicle seen in a normal form was ss ag 
a elapse i Since it was not observed until after ae oe be- 
«Since the animalcules had been placed in confineme 
1884.] Zoölogy. 831 
study of which has convinced me of the correctness of my sup- 
Only one species of Metopus has hitherto been described, M. 
sigmoides Cl. & L., and under it Stein includes several varieties 
characterized by difference in form, but passing into each other 
by gradations, the same individual assuming different shapes at 
different periods of its existence, so that a mere difference in out- 
line cannot be considered as a sufficient cause for the establish- 
ment of a new species. Stein describes three well-marked forms, 
the normal, the shortened and the rolled up. The individual 
described in the paper mentioned above was of the normal shape, 
those I have lately found may be described i 
annexed figure represents one of them 
tolerably correctly, 
y measured about .o8™™ while the 
bent-over portion constitutes about one- 
half 
plane parallel to that of the posterior por- 
h 
§ f 
o 
slightly : . $ 
pyriform outline. The axis of bas 
å nt-over portion, ör “ stirn-kuppe,” Fic. ee T 
anos at right angles with that of the posterior portion. In 
stirn-kuppe ” are a number of strongly refracting granules, 
the 
Seay by Stein, and the body is terminated posteriorly by a ` 
1 of bristle-like cilia. 
te chief points wherein this shortened form differs from that 
descri by Stein are as follows. 
Ist. The greater bending over of the anterior portion of she 
So that it is at right angles to the posterior portion, ; 
2d. The greater breadth of the body in comparison to its 
length, and the abrupt tapering posteriorly. 
iv ae Striation of the border of the bod 
y. 
description of the normal form I indicated the features 
it differs from Stein’s ; certain of these are still recog- 
I did in the shortened form, others have disappeared, and seg 
Xe hen t have an opportunity of deciding upon. The plane 
bent-over portion in the normal form is at right angles to = 
but 
