THAUMANTIAS. 41 



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, a, represents a large specimen of Geryonopsis delicatula of the natural 

 size; 1, h, shows the structure of the lips, and the origins of the gastric vessels; 1, c, is a 

 reproductive gland, the vessel passing through its centre ; 1, e?, a tentacle with its bulb ; and 

 1, e, a partially developed tentacle. 



Genus XL Thaumantias, 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 

 cymhaloidea of Slabber, and the Medusa hemispharica 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 Acalephse,' in 1843, he 

 enumerated nine species of Thaumantias, 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 T. hemisphcerica. 



Of all the naked-eyed Medusae, 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 Thaumantias, 

 of which the greater number are all so very distinct from each other, that they cannot 

 be confounded. I beheve 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: — 



