Meduse of the Philippines and of Torres Straits. 187 
The 8 mouth-arms resemble those of C. tuberculata, but there are window- 
like openings in the lateral membranes, as in Lobonema smithit. The total 
length of each arm is 81 mm., the upper arm being one-fourth as long as the 
lower arm. At their widest part the arms are about three-fourths as wide as 
they are long. The center of the arm disk is thickly covered with slender 
filamentous appendages which terminate in nematocyst-bearing, swollen, 
knob-like ends, as do the appendages of the mouth-arms of C. tuberculata. In 
this Philippine Island medusa the appendages of the outer parts of the mouth- 
arms are much less numerous and smaller than in C. tuberculata, but are similar 
in general form to those of the Mediterranean medusa. The longest are about 
15 to 20 mm. long. 
The cruciform central stomach gives rise to about 140 radial-canals, the 
8 rhopalar canals being about twice as wide as the others, instead of being of 
the same calibre, as in C. tuberculata. All these canals anastomose in a 
network under the zone of the circular muscles. There is no distinct ring- 
canal. In formalin the specimen is dull uniform yellowish-brown. 
It differs from Cotylorhiza tuberculata in having no radial-muscles, and in the 
circular muscles being interrupted in the 8 principal radii. The subgenital 
ostia and arm-disk are larger and the appendages of the mouth-arms smaller 
and fewer than in C. tuberculata. Moreover, the peculiar window-like open- 
ings in its mouth-arm membranes at once distinguish this species. 
These distinctions are indeed of such a nature that if one felt so inclined a 
new genus could be established to receive this medusa. I believe, however, 
that its relationships will be more clearly indicated by placing it in the genus 
Cotylorhiza, within which it forms a well-marked species. 
Genus CATOSTYLUS L. Agassiz, 1862. 
Catostylus (in part), Acass1z, L., 1862, Cont. Nat. Hist. U. S., vol. 4, pp. 152, 153. 
GENERIC CHARACTERS. 
Rhizostomata triptera, in which the mouth-arms bear neither clubs, filaments, 
nor other appendages. 16 radial-canals, 8 rhopalar, and 8 adradial. The 
rhopalar-canals extend to the bell-margin, but the adradial-canals end in the 
ring-canal. On both its inner and outer sides the ring-canal gives off anasto- 
mosing vessels which may join with the radial-canals, but which do not connect 
directly with the central stomach. Among characters of minor importance, 
the marginal zone of circular muscles in the subumbrella is only partially 
interrupted in the 8 principal radii. There is an exumbrella pit with radiating 
furrows above each sense-organ. 
Catostylus purpurus Mayer. 
Catostylus purpurus, Mayer, 1910, Meduse of the World, vol. 3, p. 671, fig. 412.—Liaut, 1914, 
Philippine Journ. of Science, vol. 9, p. 207. 
This form is closely related to Catostylus stiphropterus, from Ternate, but 
differs in the number and arrangement of its marginal lappets, and in its deep, 
uniform purple-brown color. Light (1914) describes this medusa from life, 
whereas Mayer had only preserved material. In life the bell is higher than a 
hemisphere, whereas in its contracted state in preservative fluids it is flatter 
than a hemisphere. When mature it is deep purplish brown, and the sense- 
organs have brilliant silver ocellus-like spots which are larger in small than 
in full-grown medusze. When young the medusa may be plum-colored, or even 
translucent white. Small cyclops-like crustacea were found by Light to be 
commensal with this medusa, the crustaceans lying upon the rhopalar canals 
close to the sense-organs. 
