430 Wisconsin Academy of Sciences, Arts, and Letters 
PEOALES DAPHNICOLA Thompson. 
Plate XVIII, figures 1-5. 
Proales daphnicola Thompson, Science Gossip, vol. 28, 1892, p. 220, fig. 
125.— Murray, Trans. Eoyal Soc. Edinburgh, vol. 45, 1906, p. 179, pi. 6, 
fig. 26. 
f Pleurotrocha sigmoidea Skorikov, Trav. Soc. Nat. Kharkov, vol. 30, 1896, 
p. 284, pi. 7, fig. 8. 
Pleurotrocha daphnicola Harring, Bull. 81 U. S. Nat. Mus., 1913, p. 84.— 
Myers, Proc. U. S. Nat. Mus., vol. 52, 1917, p. 478, pi. 41, figs. 4-9. 
The body is spindle-shaped, short and stout; its greatest width 
is about one third of the total length. The integument is soft and 
flexible, but the outline is fairly constant. It is a moderately trans¬ 
parent species. 
The head is short, broad and truncate anteriorly; it is separated 
from the abdomen by a well-marked constriction. Its width is 
about two thirds of the greatest width of the body and the length 
considerably less. The abdomen is somewhat pyriform, ending in 
a broad, but not very prominent tail. The foot is short and very 
stout; it has two joints, the basal somewhat longer and broader 
than the terminal, which is obliquely truncate posteriorly. The 
two toes are short, stout, and bluntly conical, ending in a minute 
tubule, through which the mucus glands discharge their contents. 
The dorsal antenna is a small, setigerous papilla in the normal 
position; the lateral antennae are near the middle of the body. 
The corona is very slightly oblique; the marginal ciliation is 
relatively weak, with the exception of two lateral auricle-like areas 
with very strong cilia adapted to swimming. The apical plate is 
large and unciliated; the buccal field is evenly covered with short, 
close-set cilia. The mouth is near the ventral edge of the corona. 
The mastax is very robust and furnished with powerful trophi, 
closely resembling the malleate type. The fulcrum is short and 
very broad. The rami are of an unusual form. The basal apophy¬ 
sis is very large and almost as long as the ramus itself, from which 
it is separated by a very deep sinus; the dorsal end curves down¬ 
wards. The main portion of the rami is a broad, nearly rectangu¬ 
lar plate; the inner margins are not dentate, but' form small pro¬ 
jecting cones at their junction with the dorsal margin. The right 
uncus has three clubbed teeth, gradually decreasing in size from 
the ventral margin, followed by three linear teeth; the basal plate 
is nearly square. The left uncus has three clubbed and two linear 
teeth. The manubria are roughly equilateral triangles; the ventral 
