Holothurians allied to Cucumaria frondosa (GUNNER). 605 
has a mean length of 10,6 with a range from 4—20, and a mean 
dorso-ventral diameter of 3,8, with a range from 1,4—6,3. 
Color. — The alcoholice specimens agree with Oucumaria 
frondosa. 
Tentacles. — Ten, large and equal. 
Pedicels. — The pedicels agree in arrangement with those 
of Cucumaria frondosa but are more prominent, especially upon the 
introvert where they are often found almost to the bases of the 
tentacles. 
Genital papilla. — As in Cucumaria frondosa sex differen- 
tiation is shown in the usually simple conical genital papilla of 
the female and the subdivided papilla of the male. 
Spicules. — The prevalent type of spicule in the body-wall 
is an elongated, rather thick knobbed perforated plate (Fig. 17) 
with a mean size of 150 x 43 «. The length is often 5 or 6 times 
the breadth thus giving such plates a rod-like form. About 30%, 
of the plates are irregularly rounded (Fig. 18) and in these the 
mean number of holes is 4, with a range from 1—13, or more. In 
addition, especially in the young, there is a second class of larger, 
heavier irregular plates (Fig. 19) with a mean size of 144 x 102 u. 
Their holes are comparatively large, the mean diameter being 25 « 
and the mean number, 6. The spicules are often numerous and 
crowded. In most specimens there are no masses of large plates in 
the body-wall of the cloacal region as in Oucumaria japonica but 
5 small rudimentary anal teeth are noted by Lupwıs, 1881. 
The pedicel spicules are similar to the general class of elon- 
gated plates found in the body-wall and there are multiple end- 
plates, as Lupwıc, 1881, describes. In the tentacles the supporting 
structures are mostly rod-like (Fig. 20), with fewer perforations. 
Polian vesicle. — There is considerable variation in the 
location and number of the Polian vesicles but nothing at all 
homologous to the indefinite number and distribution of these organs 
in the genus Holothuria (cf. EpwArps, 1908). Of the 33 specimens 
examined, 29 (88°/,), have at least 1 vesicle arising from the ring- 
canal in the left dorsal interradius. This may be called the primary 
Polian vesicle and taken to represent the modal state as in (Oucu- 
maria frondosa albeit there are 16 (50°/,) with more than 1 vesicle. 
Of these, 6 have 2 vesicles, 4 have 3 vesicles (like the two specimens 
of Lupwıc, 1881), 5 have 4 vesicles and 1 has 5 vesicles. 'The extra 
vesicles may be termed accessory Polian vesicles.. Of the 6 with 
