ORDER ACALEPHA HYDROSTATICA. ~ 489 
out-edges it. ‘The inferior is furnished with a great number 
of tentacula, of which the external ones are longer, and fur- 
nished with little ciliz, terminated each by a globule. They 
sometimes contain air; the middle ones are shorter, more 
simple and more fleshy. At the centre of all these tentacula 
is the mouth, in the form of a small projecting proboscis. It 
conducts to a simple stomach surrounded with a sort of 
glandulous substance. 
But one species is known of a fine blue, belonging to the 
Mediterranean, and to warmer seas. (Medusa wmbella, Miill.) 
VELELLA, 
Have, like the porpite, at the inferior face, a mouth in the 
form of a proboscis, surrounded with innumerable tentacula, 
of which the external ones are longer; but the latter are not 
ciliated, and what gives a more important character is, that 
the cartilage, which is oval, has on its upper face a vertical 
crest placed obliquely, and sufficiently raised. This cartilage 
is transparent, and has only concentric strie. 
One species is also known of the same colour, and living 
in the same seas, as the porpita. Itis eaten fried. It is the 
Medusa velella, and Holothuria spirans of Gmelin. 
THE SECOND ORDER OF ACALEPH.. 
ACALEPHA HYDROSTATIC, 
ARE recognized by one or more vesicles, usually filled with 
air, by means of which they are suspended in the water. 
Appendages singularly numerous, and varying in form, some 
