1894.] Zoology. 181 
ZOOLOGY. 
Reappearance of the Freshwater Medusa, Limnocodium 
sowerbii.—Mr. E. Ray Lankester reports finding well-grown speci- 
mens of Limnocodium sowerbii in the Victoria Regia tank of the Shef- 
field Botanic Gardens. This jelly-fish was first noticed in 1880 in Re- 
gent’s Park, to which it had probably been transported from Brazil on 
the rootlets or leaves of a Pontederia. It was observed from year to 
year until 1891, when all trace of it was lost, and naturalists gave up 
the hope of carrying on any further investigation into its life history. 
Its appearance in Sheffield is accounted for by presuming that some. 
reproductive germs were attached to the water plants sent from Re- 
gent’s Park to re-stock the tank in Sheffield, April 4, 1892, and April 
T, 1893. The curious thing is that in 1892 and 1891 no Limnocodium 
Were seen in the original source, nor in 1893 except the few sent from 
Sheffield and placed there by Mr. Sowerby. 
This beautiful little organism was first studied by E. Ray Lankes- 
ter, who ascertained the following facts. 
The jelly-fish appear suddenly each year as early as April or as late 
48 August, and remain from five to twelve weeks, when they die down 
and absolutely disappear. When first seen they are extremely minute, 
vo of an inch in diameter, and gradually develop to the full size of half 
aninch in diameter. Of the many hundred specimens examined in 
successive years, every one without exception were males. They pro- 
duced abundant motile spermatozoa, but not a trace of egg-cell has 
ever been found in any one of them. 
In 1884 Dr. A. G. Bourne described a diminutive polyp, not more 
than 4 of an inch long, devoid of tentacles which he found adhering to 
the root filaments of Pontederia in the same tank in which the Limno- 
codium was discovered. This polyp was supposed to be the “tropho- 
Some” of the Limnocodium medusa. That this inference was true was 
Proved Dr. Fowler in 1890, who was fortunate in seeing the little 
spherical young found floating in the tank, nipped off by a process of 
transverse fission from the free ends of the minute polyps described by 
Bourne, 
The next question, How do the polyps originate? has not yet been 
answered. They increase by budding, but never form colonies of more 
than four “ persons.” 
In Conclusion, the author refers to the remarkable form worked out: 
