463 
Holothuroidea from Southern Chile — PAWSON 
P solus patagonicus Ekman 
P solus patagonicus Ekman, 1925, p. 140, text 
figs. 35, 36; Deichmann, 1941, p. 148, pi. 
30, fig. 8; Deichmann, 1947, p. 339, figs. 
1 , 2 . 
DIAGNOSIS: A small psolid, up to 20 mm in 
total length, with oral and anal valves, and radial 
teeth between them. Few scales between mouth 
and anus. Sole distinct with one or two margi- 
nal rows of tube feet. Mid-ventral radius naked. 
Sole deposits mostly four-holed knobbed buttons 
(average length 0.1 mm), together with a few 
small plates. Tentacles invested in smooth or 
knobbed perforated plates (0.07-0.17 mm in 
length). 
MATERIAL EXAMINED: Sta. 39, 30, specimens; 
Sta. 40, 1 specimen. 
description : The specimens are small (total 
length ranges from 2.5 mm to 11 mm), dorso- 
ventrally flattened, oval in outline, broadest near 
the anterior end. The dorsal surface carries 
mouth and anus, and is invested in overlapping 
plates. The ventral sole is soft. Colour in life 
"salmon-pink”; in alcohol, light yellowish-brown 
dorsally, orange-brown ventrally. The tentacles 
are orange-yellow, with some small brown spots. 
The dorsal plates are about 0.8 mm broad and 
tend to overlap towards the midline, while the 
dorsal surface is bordered by one to three rows 
of smaller marginal plates (Fig. 3, 1). The plates 
are thick, reticulated, and beset with minute 
knobs. The plates also carry a small number of 
tiny pearl-like grains, which are less common in 
smaller specimens. There are about five plates 
between mouth and anus. 
The dendritic tentacles are extended in most 
specimens, and the ventral pair are somewhat 
smaller than the rest, unbranched or weakly 
branched. There are five conspicuous triangular 
interradial oral valves (Fig. 3,2), between and 
below which lie five radial valves, which are in 
the form of elongate isosceles triangles. In a 
small number of specimens, one to four smaller 
plates lie near the base of the oral valves, but 
these are not always present. The anal aperture 
is also covered by five radial valves and five anal 
valves (Fig. 3, 1 ). 
The soft sole is semitransparent and is bor- 
dered by a ring of tube feet in a single or some- 
times double row. The mid-ventral radius is 
naked (Fig. 3, 2). 
The calcareous ring comprises five radials and 
five interradials fused together. Each radial piece 
has an anterior process with a deep, narrow 
notch. Interradials each have an anterior process 
with no notch. There are no posterior processes 
(Fig. 3, 6). The ring is turned so as to lie parallel 
with the dorsal surface of the body to correspond 
with the dorsal position of the mouth. Therefore 
the mid-ventral radial piece is the most anterior 
portion of the ring. 
The thin-walled intestine is coiled into three 
loops, and the mesentery of the posterior loop 
of the intestine lies as usual in the right ventral 
interradius. Overall, the intestine is a dark 
orange-brown in colour. A single bulbous Polian 
vesicle arises from the water vascular ring in the 
left ventral radius. The short stone canal and 
nodular madreporite lie in the middorsal inter- 
radius. 
The gonads in the larger specimens are well 
developed as two bunches of light brown tubular 
unbranched caeca, which extend for the length 
of the body cavity. The genital duct proceeds 
along the dorsal side of the calcareous ring (or 
more correctly, the "posterior” side), and opens 
to the exterior immediately behind the tentacles, 
but apparently within the oral valves. 
Apart from the dorsal surface, calcareous de- 
posits are present in the sole, the tentacles, and 
the tube feet. 
1. Sole deposits: The thin sole contains four- 
holed button (Fig. 3, 3), and some slightly 
larger knobbed or smooth plates (Fig. 3, 3). 
These deposits are sparingly scattered in the 
sole. 
2. Tube foot deposits: Each tube foot has an 
end plate (Fig. 3, 7) of average diameter 0.23 
mm, which is surrounded by some curved per- 
forated rods and plates, which may carry knob- 
like projections (Fig. 3, 3). The length of these 
deposits varies between 0.06 mm and 0.2 mm. 
3. Tentacle deposits: The tentacles are in- 
vested in a network of perforated rods and 
plates, some of which carry knobs (Fig. 3, 4). 
REMARKS: After having examined these speci- 
mens, I thought that I had found a new species, 
as they differ in some respects from Ekman’s 
(1925) type specimen. Both Ekman (1925) and 
Deichmann (1941) state that P solus patagonicus 
can have small intercalary plates between the 
larger dorsal plates. The photograph of Ekman’s 
