HYDROSTATICA, 427 
Medusz might also constitute a small family in this order, on account 
of the internal cartilage which supports the gelatinous substance of 
the body. 
Porpita, Lam., 
Where this cartilage is circular, and its surface marked with con- 
centric strize crossed by radiating striz. ‘The superior surface is 
merely invested with a thin membrane that projects beyond it; the 
inferior is covered with a great number of tentacula, the exterior 
of which are the longest, and furnished with little cilia each termi- 
nated by a globule. They sometimes contain air; those in the 
middle are the shortest, simplest and most fleshy. In the centre of 
all these tentacula is the mouth, in the form of a little salient pro- 
boscis. It leads to a simple stomach surrounded by a sort of glandular 
substance.- 
One species is known of a beautiful blue colour, that inhabits 
the Mediterranean, and seas of hot climates*, 
VELELLA, Lam., 
Where, as in Porpita, there is a mouth in the inferior surface in the 
form of a proboscis, surrounded with innumerable tentacula, the ex- 
terior of which is the longest, but the latter are not ciliated, and a 
still more impertant character is, that the cartilage, which is oval, 
has on its superior surface a vertical and tolerably elevated crest. 
This cartilage is diaphanous, and is merely marked with concentric 
striae. 
A species of this genus also is known, of the same colour as 
the Porpita, and inhabiting the same seas. It is eaten fried f. 
ORDER II. 
HYDROSTATICA. 
The Hydrostatic Acalepha are known by one or more bladders 
usually filled with air, by means of which they suspend themselves in 
their liquid element. Excessively numerous and variously shaped 
appendages, some of which probably serve as suckers, and the others 
* It is the Med. umbella, Miill., Natur. of Berl., Besch., II, ix, 2, 3; Holothuria 
nuda, Gm.; Forsk., XXVI, 1,1; and Encye., XC, 6,7; Porpita gigantea, Pér., 
Voy., XXXI, 6. : 
The Medusa porpita, L., is merely its cartilage divested of the gelatine and ten- 
tacula. 
The Porpite appendiculée, Bosc., Vers, II. xviii, 5, 6, if not an altered individual of 
the same, should constitute a separate subgenus. It is the genus POLYBRACHI- 
ONnrIA, Guilding., Zool. Journ., XI. 
+ It is the Medusa velella and the Holothuria spirans, Gm.; Forsk., XXVI, k; 
Encyc., XC, 1, 2. The Velella scaphidia, Pér. Voy., XXX. 6, is nowise generically 
different; it appears that there are several species, such as the V. oblonga, V. 
sinistra, V. lata, Chamiss, and Eisenh., Ac. Cur, Nat., X, p. I, pl. ae) 
FF 
