152 Papers from the Marine Biological Laboratory at Tortugas. 
than that I was unable to go, and am still quite in the dark as to the nature 
of these curious bits of animal life. 
Mucus masses——The presence of these larval creatures in the mucus 
clouds excreted by Cassiopea gave rise to the notion that the reproductive 
organs must secrete this mucus, which was useful as a vehicle for the sperm- 
cells. It was afterwards seen, however, that the clouds of mucus originated 
not in the genital pouches but from the oral arms. They probably serve to 
entrap and hold minute animalcules and other prey for food, having the 
same origin and function as the similar product in corals.t. These sluggish 
rhizostomes come nearer to the actinians in point of habit than do most of 
the coelenterates, and it would not be surprising to find that both their food 
and their mode of capturing it were somewhat similar. 
Failing in my attempt to get the larval stages by natural means, I tried 
artificial fertilization of the eggs, or rather I took the preliminary steps 
thereto. But I was unable to discover any sperm! All the medusz that 
I examined proved to be females, and no organs but the ovaries appeared 
within the genital pouches. Over one hundred of the medusze were opened 
in the laboratory, with the result that every individual was found to have 
ovarian eggs in the vermiform gonads, in all stages of maturation. 
It was disappointing to fail of getting the larve of this interesting 
medusa, and that, too, without having any explanation to fall back upon. 
True, it did not seem to be the normal breeding-season, prolonged search 
having brought to light only a few larve in the scyphistoma stage, and only 
a single free ephyrula. But these few young stages indicated that there 
was some activity in the reproductive functions of the members of the 
species there in the moat. At the height of the breeding-season there would 
undoubtedly be no difficulty in finding many immature stages. Bigelow 
reports that at the time of his observations in Jamaica the stones and sticks 
in Salt Pond were thick with the scyphistomas. It certainly looks as if the 
creature were hermaphrodite, and the indications are that it is also proto- 
gynous. 
Polyclonia frondosa Agassiz. 
While collecting in the moat one morning early in July, 1905, my eye 
caught the sparkle of clear white spots upon the oral arms of a medusa on 
the sandy bottom. When it was brought to the surface, these white spots 
were found to be small scales about the size and shape of an apple seed, 
except that they were flatter, attached to the surface of the arm by the small 
pointed end. The fleshy yellow tentacle-like appendages, which are so 
characteristic in Cassiopea were entirely absent, and the scales seemed to 
take their place. The general color-tone of the medusa was noticeably dif- 
ferent from that which prevails in Cassiopea. There was a more trans- 
parent appearance, with the brownish yellow turned to olive-brown, and the 
*Duerden, J. E., 1904. The Coral Siderastrea radians and its Postlarval Develop- 
ment. Carnegie Institution of Washington. Publication 20, page 6, footnote. 
