126 



Selections. 



[No. 7, NEW SERIES. 



The family of the " Sea-bladders" (Physalidce) commonly called 

 Portuguese Men-of-W ar consists of a bladder-shaped body of gela- 

 tinous consistency, on the lower surface of which are a quantity of 

 worm-like sucking apertures, feelers and very lengthy seizing- 

 threads. The body consists generally of 2 bladders which envelop 

 each other, the inner one being completely closed and filled with 

 air, while the outer one has a comb at the top, which the animal 

 uses as a sail when swimming. The outer gristly bladder is used 

 too as a covering for the threads and feelers, which can draw them- 

 selves back into it: see fig. 4, plate v. Little bunches of reel bodies 

 are often found at the base of the sucking-tubes, and have been 

 supposed to be eggs. These beautiful animals of a delicate pink 

 and blue color swim in crowds on the surface of the southern 

 ocean, and when touched can sting so severely that they were for- 

 merly considered poisonous. Physalia, Discobale. 



The family of the " Gristle-medusas" (Velellidce) possesses a cel- 

 lular disc of a gristly substance, sometimes containing calcareous 

 deposits, and on the lower surface of which the bodily organs are 

 placed ; — see fig. 5, plate v. The cells of the disc are filled with air 

 and thus give the body a certain specific lightness. In the middle 

 of the lower surface of the disc is a large opening which some con- 

 sider to be the mouth ; around it are many small oj)enings, also 

 of a vermicular form, which some have considered to be feelers, 

 and others sucking apertures. At the base of these are to be seen, 

 little clusters of small bodies the purpose of which is still doubt- 

 ful. The animals of this family which are generally of a beautiful 

 blue, appear at certain times in countless swarms in the Medi- 

 terranean, and in the ocean within the Tropics. The genus Ve- 

 lella, the only one in the Mediterranean, has a sharp upright comb 

 on the disc, while the genus Por^)ita which inhabits the Southern 

 seas has a simple round radiated cellular disc. Velella, Porpita. 



The family of the " Double-medusa)" (Diphyidce) consists of a 

 number of more or less united beings, the structure of which is 

 much more complicated than that of the preceding animals. There 

 are to be found in the sea single bodies of a glassy transparency, 

 which however consist of two pieces, a covering piece, and a flap- 



