42 
The Philippine Journal of Science 
1921 
One interesting thing noted about this medusa was its ability 
to free its nematocysts or its poison on being handled or moved 
about by the waves. This is particularly noticeable when speci- 
mens are lifted from the water and returned. Persons standing 
in the water within a radius of five feet experience a most un- 
pleasant, but merely temporary, burning and itching sensation 
on those parts of the body at the surface even though covered 
with a bathing suit. I am told that when these forms are 
numerous bathing becomes unpleasant along the exposed water 
front, due to the release of this poison or the nematocysts by 
the medusae which are beaten about in the surf. 
IMMATURE FORMS 
This species evidently completes its life cycle in the bay since 
very small forms are abundant at times. Several collected by 
Doctor Shaw in June, 1920, show interesting stages in develop- 
ment. The smallest of these is 7 millimeters in diameter. The 
central mouth is just closing, being closed at the center with the 
four corners still open. Three of the four corners of the mouth 
have begun to bifurcate forecasting the 8-armed condition of the 
adult. Along each side of the gutterlike furrows which repre- 
sent the open portion of the mouth is a single row of tentacles. 
The centripetal vessels are represented by but a single short, 
blind canal between each two radial canals and unconnected with 
either radial canal. In this stage Catostylus which in the adult 
condition has its centripetal vessels communicating with all 16 
radial canals, and Acromitus which in the adult form has its 
centripetal vessels joining only with the 8 rhopalar, would prob- 
ably be indistinguishable. However, in a specimen 13 millime- 
ters in diameter, the centripetal vessels join the 8 adradial 
canals, while in Acromitus they join the 8 rhopalar canals and 
not the adradials. In specimens of 20 millimeters or more in 
diameter the centripetals anastomose with all the radial canals, 
as in the adult. 
Genus MASTIGIAS L. Agassiz, 1862 
Mastigias papua (Lesson) L. Agassiz. 
Cephea papua LESSON, Voyage de la Coquille, Zooph. (1829) 122, pi. 
11, figs. 2, 3. 
Mastigias papua L. Agassiz, Cont. Nat. Hist. U. S. 4 (1862) 152; 
Mayer, Medusae of the World 3 (1910) 678, fig. 415; Light, Philip. 
Journ. Sci. § D 9 (1914) 209; Mayer, Pub. Carnegie Inst. Wash- 
ington 212 (1915) 193. 
This ubiquitous medusa of oriental waters is here reported 
from Manila Bay for the first time where it appears to be present 
