ACALEPHiE. 
231 
"Pimals, one fitting into the cavity of the other; Vliysahadiv, having 
Kirg e oblong air-vessels and numerous tentacles of several forms, long, 
aud pendant from one end of the shell, with a wrinkled crest ; 1 dellctdm , 
au iwals stretching over a cartilaginous plate with a flat body, an ob- 
lique, vertical, cartilaginous crest above, a tubular mouth below, and sur- 
I'oimded by numerous short tentacles; Physophora, consisting of a 
lender and vertical axis, terminating in an air-bladder, carrying 
laterally swimming-bladders, which lose themselves amongst a bundle 
slender white filaments. 
VlLELLADiE. 
Ihe Vilellse assemble together in great shoals ; in tropical seas and 
evei i in the Mediterranean they may be seen in fine weather floating 
.' ll Hae surface of the waves. As described by De Blainville, the body 
j ° v al or circular, and gelatinous, sustained iu the interior of the 
° rsa l disk by a solid sub-cartilaginous frame, provided on the lower 
Sllr face of the disk with extensible tentacular cirri. The family 
1,1 ''Wes four genera ; namely, Vilella, the Holothuria of the Chinese, 
Uc h the reader will most readily comprehend from the brief descrip- 
l0n we shall give of the Mediterranean Vilella (F. limbosa— Fig. 03), 
