GERYONIAD. 
Genus VIII. Gerryonta, Peron (1809). 
Umbrella hemispheric, margin furnished with tentacula in variable number, 
usually few; radiating vessels five; ovaries four, phylliform, on the surface of the 
sub-umbrella in the course of the vessels ; peduncle rather long, conico-cylindrical, 
terminating in a small campanulate stomach, opening by four lips. 
Geryonia appendiculata, Forbes. 
Plate V, Fig. 2. 
One of the most phosphorescent Medusa of the British seas is the graceful little animal 
I have now to describe. The umbrella is smooth, transparent, and of a hemispherical shape, 
sometimes nearly sub-globose, slightly elongating durmg the act of ascending, becoming 
more spherical when descending. The margin is fringed by eight distant tentacula, four of 
which are of a different structure from the other four; the former being cylindrical, and 
composed of similar tissue (fibrous cells) throughout, whilst the latter have an outer and inner 
side of different composition, the fibrous cells being collected in bundles or masses at regular 
intervals on the inner surface. Both orders of tentacles appear to be tubular. Those of the 
first kind are highly contractile, and capable of great extension, trailing after the body to 
twice or three times its length when the animal rises, becoming short and thick when it 
sinks. The intermediate tuberculated tentacles have not an equal power of extension. At 
the origin, and by the side of each of the more extensile tentacles, is a globular body within 
a cavity (otolitic ?) produced linearly upwards to terminate in a vesicular body, also with 
contents (a rudimentary ocellus 7). A similar, though smaller and less defined, structure is 
seen at the bases of the intermediate tentacles. Opposite to each of the longer tentacles is a 
simple gastric vessel joining a marginal one, and proceeding down the inner surface of the 
rather conical and truncated sub-umbrella. Towards the summit of the sub-umbrella in the 
course of the vessels are the bases of four leaf-shaped, cordate, reproductive glands (in the 
instances examined, ovaries). Round the opening of the sub-umbrella is a rather broad, 
shelf-like veil. From its centre depends a long conical peduncle, extending for half its length 
below the orifice of the disk. Its base is thick, and it tapers rather gradually nearly to the 
extremity, a little above which there is a constriction, marking the commencement of the 
broad campanulate stomach. The gastric vessels commence at this point, and run up the 
peduncle. The oral orifice is four-lobed, but these lobes or lips change form considerably, 
sometimes appearing acute, sometimes obtuse, and occasionally as if six-lobed. They are 
bordered by a highly contractile tissue composed of fibrous cells. Indistinct bands of similar 
