THAUMANTIAS. 4] 
and states that his friend Dr. Koch observed it eat mutilated fragments of the ciliograde 
Eucharis multicornis. The coarser indigestible parts of its food were ejected by the mouth 
in doing which the stomach shortened considerably, and everted itself partially. 
Plate IX, f. 1, @, represents a large specimen of Geryonopsis delicatula of the natural 
size; 1, 6, shows the structure of the lips, and the origins of the gastric vessels; 1, ¢, is a 
reproductive gland, the vessel passing through its centre ; 1, d,a tentacle with its bulb; and 
1, e, a partially developed tentacle. 
Genus XI. TuHaumanttas, Eschscholtz (1829). 
Umbrella hemispherical, in some species almost globular, in others much 
depressed ; ovaries four, varying in form from ovate to linear, conspicuous on the 
sub-umbrella in the course of four simple radiating vessels; margin of umbrella with 
tentacula in variable number (from 4 to 200) according to the species, their bulbs 
always ocellated ; stomach sessile, dependent from, and almost always included 
within the sub-umbrella ; mouth with four lips, rarely fimbriated. 
This excellent genus was instituted by Eschscholtz for the reception of the Medusa 
cymbaloidea of Slabber, andthe Medusa hemispherica of Gronovius. The latter is so much 
better known than the first, that it may be regarded as the type. They are probably, 
however, identical. When Lesson published his ‘ History of the Acalephz,’ in 1843, he 
enumerated nine species of Zkaumantias, two of them Norwegian, discovered by Sars, and 
four British, described by myself in the ‘ Annals of Natural History.’ The ninth was the 
Medusa lucida of Macartney, another name for 7. hemispherica. 
Of all the naked-eyed Medusz, those belonging to this genus are most common in our 
seas, swarming in countless myriads in many of our bays and harbours. They are among 
the most usual causes of phosphorescence. It might be expected that animals so 
abundant, when carefully sifted, although so similar, would be found to include several 
distinct kinds. I have now to describe no fewer than seventeen British species of 7haumantias, 
of which the greater number are all so very distinct from each other, that they cannot 
be confounded. I believe many more equally distinct will be before long discovered in the 
European seas. 
The characters in common presented by many of these kinds are such as to enable us 
conveniently to group them in sectional assemblages, dividing them, in the first instance, 
under two sub-generic heads:— 
