A Description of three Acoela from the Gulf of Naples. 
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in length. The color, a pale canary yellow, shading into white, is due 
to a diffuse pigment, and not to special pigment cells. There are no 
zoochlorella cells present. The "diffuse eyes" which Uljanin mentioned, 
are small masses of concrement in the region of the mouth. When the worm 
is swimming or suspended near the surface of the water this concrement 
appears as a dark mass in the anterior end of the body. Examination 
of the worm when shghtly compressed under the cover-glass, proves 
that the black color is due to the opacity of the concrement. At times 
a great accumulation of oil globules in this region makes the animai ap- 
pear almost translucent. 
The behaviour of these small animals is characteristic. They swim 
rapidly from place to place, but when undisturbed in an aquarium, they 
gather in masses around the sides of the glass with the tail end down, 
and the blunt anterior end just below the surface of the water. This 
coUecting of the individuals is of advantage to the investigator, for hun- 
dreds of worms may be drawn up together in a small pipette. They are 
exceedingly sensitive, and are therefore not at ali well adapted for ex- 
perimentation. One may succeed in keeping them alive in glass dishes 
for forty-eight hours if the water is changed at frequent intervals. 
ÄpJianostoma pulchella is pelagic, and is obtained near the shore at 
a depth of one to two meters. I have never seen the worms crawling 
on seaweed. 
c) Anato my. 
The surface of the body is cihated, the cilia being arranged in longi- 
tudinal rows (pi. 10, fig. 1, c). So far as I can determine these rows 
are not oblique, but frequently appear so owing to the twisting and turn- 
ing of the worm. The integument is vejy thick, and conspicuous, as 
seen in the transverse sections (figs. 1—4). It consists of tali epithelial 
cells with deeply staining nuclei. Scattered among these cells at more 
or less regulär intervals, are largo glands. The worm is not highly mus- 
cular, its movements are largely due to the lashing of the ciha. Definite 
muscle fibres were not visible in any of the preparations. 
The largo glandulär mass (pi. 10, fig. 1, fg) to which the name frontal 
gland has been given, occupies the entire anterior end of the body. The 
occurrence of this gland among the acoelous flatworms is frequent. Löh- 
ner and MicoLETZKY distinguish two types of frontal glands those which 
open by separate ducts on the anterior surface as in Polychoems caudatus 
Mark, and those in which the ducts converge into one common duct. 
This type is illustrated in Convoluta roscoffensis. The frontal gland of 
