20 WILLSIA STELLATA. 



nearly colourless margin. The six ovaries together form a beautiful star around the base of 

 the stomach. Each gastro-vascular canal runs without dividing through the corresponding 

 ovary, but when it reaches half way down the sub-umbrella, it divides into two, and at a 

 fourth of the distance between the margin and the centre, each branch again divides into two, 

 which is the final division, for these last two branches run directly into the marginal canal, 

 each opposite the origin of a tentacula. 



The Willsia stellata was first observed by Mr. M'Andrew and myself, in September, 

 1845, in the Bay of Oban. Many specimens occurred, and its appearance in the vessel of sea- 

 water, was very striking, the star-like ovaries conspicuously distinguishing it from Medusae 

 of other genera. It is so transparent, that usually only the reproductive star and the mar- 

 ginal circle of brilliant ocelli — like a mimic sun with its surrounding planets — could be 

 perceived by the naked eye. When placed in a watch-glass, however, the singular arrange- 

 ment of its vessels, and the other details of its structure, may easily be made out without the 

 use of a high magnifying power. 



In August, 1836, when visiting Penzance Bay, we took great numbers of the same 

 species, so that it would appear to be rather widely distributed. It was not observed at 

 Zetland, nor further west than the Lizard on the south coast of England. 



In the Plate, fig. 1 represents the natural size ; 1, a, a magnified view as seen from the 

 side ; 1, h, the creature seen from above ; 1, c, the mode of division of one of the gastro- 

 vascular trunks ; \,d,wv ovary ; and 1, e, a tentacle, both greatly magnified. 



