THE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
[FIFTH SERIES.] 
No. 15. MARCH 1879. 
XX.— On an Anomaly among the Hydromedusce , and on 
their Mode of Nutrition by Means of the Ectoderm. By 
C. Mereschkowsky. 
[Plate XX.] 
In one of my former articles on the Hydroids * I mentioned, 
among other things, a new species of small Medusa belonging 
to the genus Bougainvillea , which I named Bougainvillea 
paradoxa , but without giving any description of it. A very 
short description of it has been given in Russian in the Trans¬ 
actions of the Society of Naturalists of St. Petersburg f. 
Here I shall only speak very briefly of the normal Medusa 
itself, as it is my intention to make another journey to the 
White Sea, and to make a more detailed investigation of this 
interesting organism than I have hitherto been able to do. 
In the present note I shall refer especially to a strange ano¬ 
maly which may be pretty frequently observed among the 
normal individuals of Bougainvillea paradoxa , and to its 
physiological consequences. 
The adult Medusa does not much exceed 1 centim. in 
length. Its form (PI. XX. figs. 1 and 5) is that of a bell 
slightly contracted at its aperture ; there are four radiating 
canals, each furnished at its extremity with a tuft of from three 
* a Studies on the Ilvdroida,” Ann. & Mag. Nat. Hist. ser. 5, vol. i. 
April 1878, p. 323. 
+ Protocolles de la Reunion du 14 Janvier 1878, in vol. ix. p. 33. 
Ann. A Mag. N. Hist. Ser. 5. Vol. iii. 12 
