MARINE PROTOZOA FROM WOODS HOLE. 
457 
normal these are pointed and curve abruptly to the right. Two smaller cirri lie to the left of the 
group of anal cirri. The peristome is well-marked by the adoral zone, and upon its right border there 
is a row of cilia, and a similar row of cilia runs along the base of the oral membranelle. The macro- 
nucleus is double and consists of two elongate cylindrical masses lying parallel with one another. 
One of these is in the anterior region; the other is posterior. The contractile vacuole lies dorsal to 
the anal cirri and anterior to the three dorsal cirri. The movement and general activities resemble 
those of Euplotes. 
Length 50/; ; diameter 25/;. 
Genus URONYCHIA Stein ’52. 
(Stein ’59, ’07; Quennerstedt ’67; Kent ’81; Bi'itschli ’88.) 
Medium-sized colorless ciliates of usually constant body form. The body is somewhat short and 
oval in outline. The anterior end is broadly truncate, the posterior end rounded or slightly pointed. 
The ventral and dorsal surfaces are considerably arched and the latter usually has a number of rows 
of longitudinal stripes. The open peristome is broad and 
reaches back to the middle of the ventral surface and 
beyond. According to Stein, the two edges can approach 
each other, thus opening and closing the peristomial area. 
Its right edge forms a greater angle with the front edge 
than in the genus Euplotes, and the left edge forms a greater 
angle with the front edge than in that genus. The left 
edge also appears to cover over the adoral zone slightly. 
There are no ventral cirri in front, but on the posterior 
ventral surface are 7 great springing cirri. Five of these 
are inserted on the right side in a deep in-sinking, and the 
other 2 in a similar depression on the left ventral surface. 
Above the 5 right-side cirri, i. e., dorsal to them, but in 
the same depression, are 3 angular cirri. A few edge cirri 
are found to the left of them and another to the right of 
the 5 cirri. The contractile vacuole is on the left side 
between the main groups of cirri. The macronucleus is 
band-form or spherical, and is situated in the middle region 
of the body. Movement consists in forward swimming 
with sudden springs. 
Salt water. 
Uronychia setigera, n. sp. Fig. 55. 
This species is very common in the Woods Hole 
waters. It is small, colorless, and very active. The most 
characteristic feature is the posterior end with its relatively 
enormous cirri, which are apparently large enough for an animal four times its size. The form is 
ovoid, widened posteriorly. 
The ventral surface is flat and has two excavations in the posterior end. The right hollow is larger 
and contains 5 great cirri of unequal size, the extreme right one being the largest. The left hollow 
contains 2 cirri, also of dissimilar size. Dorsal to the 5 right cirri are 3 sickle-formed cirri, which are 
usually fimbriated. These are pointed and curve regularly to the left. The peristome is wide and 
open, and a small pocket, -like hollow on its left border indicates the region of the mouth. The adoral 
zone runs into this pocket and the mouth is located in its lower right-hand corner. In U. transfuga 
the right border is generally described as having a membrane of extreme delicacy. I was unable to 
see such a membrane in this form, but in its place there are 2 flagella-like cirri extending from the 
margin of the mouth opening into the peristome, and these vibrate slowly. I do not believe these 
could be the moving edge of an undulating membrane, for they are quite distinct. The macronucleus 
is spherical instead of band-form, and a single micronucleus is closely attached. This is unlike the 
European species U. transfuga, in which the nucleus is elongate. The contractile vacuole lies between 
the two sets of posterior cirri. There are no marginal folds like those of the European species. 
Length 40//; width 25//. Common. 
Fig. 55. — Uronychia setigera. 
