464 
PACIFIC SCIENCE, VoL XVIII, October 1964 
(1925) specimen clearly shows these plates. 
None of the specimens I examined possess these 
intercalary plates. Ekman’s specimen was 20 mm 
long, while the largest in the present collection 
is 11 mm in total length. This size discrepancy 
could explain the absence of intercalary plates 
in my material, as they may develop later in the 
life of the animal. 
The present specimens closely resemble the 
type of P. patagonicus when their calcareous de- 
posits are considered, and thus there is little 
doubt that they are in fact examples of Ekman’s 
species. 
DISTRIBUTION: The type specimen (Ekman, 
1925) was collected from the Patagonian bank, 
46° S, at a depth of 110 m. Deichmann (1941, 
1947) states that the species has been taken 
from the type locality and various other localities 
in the Straits of Magellan. Present records in- 
dicate that Psolus patagonicus may be quite 
common in some localities, its small size per- 
haps enabling it to escape notice by the collector. 
ORDER APODIDA 
Family CHIRIDOTIDAE 
Genus Chiridota Eschscholtz, 1829 
Dactylota Brandt, 1835; Liosoma Brandt, 1835; 
Trochinus Ayres, 1852; Lio derma Bronn, 
1860. 
DIAGNOSIS: Tentacles 12, digits 3-10 on each 
side, the terminal pair being the longest. Polian 
vesicles numerous (3-20). Deposits six-spoked 
wheels collected into small papillae containing 
varying numbers of wheels of diverse sizes. No 
sigmoid rods, but small curved rods with en- 
larged ends may be present. Minute miliary 
granules often occur in the longitudinal muscles. 
TYPE SPECIES : Chiridota discolor Eschscholtz. 
REMARKS: This is a well-defined genus of 
world-wide distribution, containing about 25 
species, none of which have a very extensive 
geographic range. Most species occur in shallow 
waters, although some have been taken at depths 
in excess of 3,500 m. 
Chiridota pisanii Ludwig 
Chiridota pisanii Ludwig, 1886, p. 29, pi. 2, fig. 
14; Ludwig, 1898^, p. 71 (complete list of 
references); Ludwig, 1898$, p. 445; Clark, 
1907, p. 118; Ekman, 1925, p. 145, text fig. 
62; Heding, 1928, p. 297, text fig. 62; 
Heding, 1931, p. 676; Deichmann, 1947, 
p. 347. 
Chirodota purpurea Theel, 1886^, pp. 15, 35, pi. 
2, fig. 1; Lampert, 1889, p. 851. 
DIAGNOSIS: Tentacles 12, usually with five 
pairs of digits each. Calcareous deposits wheels, 
which are arranged in papillae up to 1.5 mm in 
diameter. Papillae confined to the interradii, and 
are more numerous dorsally, where they are ar- 
ranged in a single row in each interradius. No 
other deposits in the skin. Radial muscles con- 
tain miliary granules. Tentacle rods bracket- 
shaped, with branched ends, average length 0.05 
mm. 
material examined: Sta. 73, four speci- 
mens. 
REMARKS: The total length of the four speci- 
mens ranges between 1 1 mm and 60 mm. Colour 
in alcohol dirty white to light brown. There are 
12 tentacles, each with five pairs of digits. The 
wheel papillae vary considerably in diameter, up 
to a maximum of 1 mm. 
Dissection of the largest specimens revealed 
the presence of seven Polian vesicles, the largest 
being 7 mm in length. Rows of closely aggre- 
gated ciliated funnels lie in the middorsal and 
left lateral interradii, the rows commencing 
about 6 mm from the anterior end of the body 
cavity, and extending to the extreme posterior 
end. The genital tubules are long, sparsely 
branched, and packed with eggs averaging 0.3 
mm in diameter. Deichmann (1947) has com- 
mented on the relationships of this species, and 
notes that deeper water forms are known which 
may perhaps be assigned to Chiridota purpurea 
Theel. 
DISTRIBUTION: Chiridota pisanii is known 
from both coasts of southern South America, and 
the Falkland Is., from the intertidal zone to 
about 100 m. 
Genus Prochodota Ludwig, 1892 
DIAGNOSIS: Tentacles 10, digits 2-6 on each 
side. One Polian vesicle and one stone canal. 
Calcareous ring comprises 10 pieces, the radial 
imperforated. Calcareous deposits sigmoid hooks, 
scattered or arranged into groups, and wheels, 
