222 TEAysAcrioKS of the American Institute. 



time the best naturalists included them in the same class. On further 

 study it was shown that the softer portions of this animal were of the 

 utmost simplicity, that the little chambers of the shell were filled with 

 a substance almost homogeneous, and resembling the amoebse, and 

 that this matter could be projected in fine threads through the many 

 holes which ornamented the shell, performing locomotive acts and 

 combining together to form simple stomachs. This little chambered 

 shell is also filled with some simple substance which projects in fine 

 threads through the many minute perforations of the shell, and per- 

 forms the act of locomotion and digestion as in amoeba. 



Another condition peculiar to many animals is their fixed condi- 

 tion. In all the branches except the vertebrates, members are found 

 which have no power of locomotion, always adhering to some sub- 

 stance. Many of the lowest animals, like the sponge, are fixed, 

 growing in communities, like the coral builders. The crinoids, or 

 stemmed star-fishes, are attached by a stem to the rock. Many of 

 the lower shell-fish, and certain low worms and the barnacles are 

 always fixed, though many of these, in their younger stages, are loco- 

 motive animals, as the barnacle, for example, which, upon issuing 

 from the egg, remotely resembles the young of the crab and lobster, 

 is furnished with eyes and skips about in the water for some time. 

 Afterward it becomes aflixed, head downward, to the rock, or what- 

 ever appropriate substance it may meet with, and becomes stationary 

 for life. Many of these fixed animals are parasitic on other species ; 

 the whale being oftentimes covered with a peculiar barnacle ; and 

 other animals might be mentioned which are likewise parasitic ; then 

 there are certain species which become attached to floating timbers 

 or to sea weed, and even the bottoms of vessels are frecpiently so 

 thickly covered with species of this nature as to materially retard 

 their speed. In other cases only the earl}^ condition of certain ani- 

 mals are attached, as in the discoid jelly fishes, the joung is rooted 

 to some spot, and reminds one of the polyps, to which group they 

 were at first referred; by successive divisions of .this unit, a number 

 of little jelly fishes are produced. This attached condition of animals 

 may be called a vegetative character, and is a sign of degradation, 

 and we find only the lowest forms of certain groups attached. 



Another form of locomotion is seen in certain animals where a 

 large portion of the body is formed into a creeping disk. [The lec- 

 turer then rapidly illustrated, on the board, various worms, snails, 

 &e.J Tlie sea anemone has slight powers of locomotion through a 



