600 CHARLES LincoLn EDWARDS, 
feels rough. Sometimes the spieules of the cloacal region of the 
body-wall occur in heaps which are not so compact, or made of such 
large plates as the similarly located spieules of Oucumaria japonica. 
In the deepest layers formless calcareous deposits are often found. 
The spicules of the pedicels (Pl. 19, Fig. 3), are somewhat 
elongated perforated plates with one end rounded or with several 
prongs, and the other spinose and projeeting from the surface. The 
end-plates are sometimes simple in the young but in the adult they 
are always multiple, being made up of from several to many rods, 
rosettes, or simple plates, in one case of 65 such elements. 
T'he spieules of the tentacles (Fig. 4), are elongated, knobbed, 
straight or curved rods and plates, being smaller distally. In some 
cases the spicules have been absorbed leaving clearly evident spaces 
in the tissues. Teater, 1886, claims that in small individuals the 
plates are common dorsally, while rare or totally absent ventrally. 
As described in my earlier papers (1909, 1910), there are 5 small 
radial vestigeal anal teeth. 
Calcareous ring. — The calcareous ring is not always per- 
fecetly preserved. All of the 5 radialia and the 5 interradialia have 
anterior prolongations and are notched posteriorly, the radialia being 
somewhat larger. 
Polian vesicle. — There is one prominent Polian vesicle 
arising from the ring-canal in the left dorsal interradius. In 6°), 
of the specimens there is in addition an extra vesicle from another 
interradius. 
Stone-canal. — The single stone-canal has a mean length 
of 5mm. The spherical madreporite is greatly convoluted and has 
a mean diameter of 1 mm. 
Gonads. — The gonads are in two tufts, one to the right and 
one to the left of the median dorsal enteric mesentery. 
Respiratory trees. — The right and left respiratory trees 
diverge from a common base at the anterior end of the cloaca. Each 
tree consists of a major, primary stem, in a lateral dorsal inter- 
radius, and of a minor, secondary stem, in a lateral ventral inter- 
radius. 
Muscles. — The radial muscle bands and the introvert re- 
tractors are simple but thinner along the median line, where in 
some cases the introvert retractors may split into paired bands. 
The eireular muscles and cloaca extensors are also well developed. 
