ACALEPH 2. jas | 
Note. If the figures in Forskau, Tab. xxvi. fig. k3, k4, k5, belong to 
a young Velella, as appears from the explanation of the plate, this genus 
must be suppressed ; which is BLATNVILLE’S opinion. 
Porpita LAM. The Lamina cartilaginous (?), circular, marked 
with concentric striz decussated radially. Marginal tentacles 
appendiculate. 
Sp. Porpita mediterranea Escuscu., Porp. Forskalii, DE Haan, Hol. denu- 
data Forsx. Icon. Rer. nat. Tab. xxvi. fig. L., in the Mediterranean ;— 
Porp. umbella Escuscu., Porp. gigantea PRON, Voy. aua terres austr. 
Pl. xxxt. fig. 6, in the Tropical Seas; Porp. chrysocoma Luss., GUERIN 
Iconogr., Zoophytes, Pl. xvi. f. 2—(Medusa Porpita L. is merely the 
cartilaginous disc of some species of this genus.) 
Family Il. Physsophoride (Hydrostatica Cuv.) Body sus- 
pended in the water by means of a swim-bladder or of receptacles 
filled with air. 
Bladder-bearers. The opinion that these animals are able to 
expel the air from the air-bladder at will was rendered doubtful, as 
a general rule, by OLFEeRs, who could find no opening in the large 
bladder of Physalia. [Subsequent observations however have deter- 
mined that Physalia is the only one of the Physsophoride whose 
bladder does really communicate with the external air. But, though 
there be no such communication in the rest, LEucKART states that 
in many of them (and he believes it to be true of all) the air may 
be readily caused to pass from the cavity of the bladder into that of 
the common stem, by the expansion of the upper extremity of which 
the air-bladder is in all cases surrounded. 
a) with short stem or axis without swimming bells. 
Physalia Lam. Swimming bladder very large, crested above, 
with an aperture at one extremity: the whole of the common stem 
expanded so as to form a receptacle for it: from the inferior surface 
of the expanded stem the polyps are suspended together with 
feelers and prehensile organs, of different thickness and of great 
length.] 
Sea-bladder. The colony swims constantly on the surface of the 
sea, and for that purpose makes use of the crest on the top of the 
bladder as a sail. Hence its name, het bezaantje, the Portuguese 
man of war, la petite galére, &e. Ifin the nomenclature we ought 
strictly to hold to priority, then this genus ought to be named 
