THE 
AMERICAN NATURALIST. 
VoL. x.— NOVEMBER, 1876. — No. 11. 
A REMARKABLE LIFE HISTORY AND ITS MEANING." 
BY W. K. BROOKS. 
AVIGATORS in tropical seas often speak of sailing for days 
through regions where the water of the ocean, to a depth of 
many feet, is filled with small transparent animals, which are 
attached to each other in such a way as to form chains or trains 
like trains of cars. Although these animals are perfectly transpar- 
‘nt and jelly-like in appearance, the fact that their bodies are of 
sufficient consistency to admit of their being somewhat roughly 
handled, or even removed from the water, without essentially 
changing their shape, at once distinguishes them from such ani- 
mals as jelly-fishes ; and a very superficial examination is enough 
to show that they are quite different from these in organization. 
ey belong to the group Tunicata, animals which have been 
with the Mollusca, although we now know that the re- 
semblances which formerly led naturalists to this idea of their 
affinity are merely superficial, and without scientific value. 
Most of the Tunicata are, in their adult state, attached to 
heavy bodies which rest upon the bottom of the ocean; stones 
ind shells, for instance. .A few, however, are locomotive and are 
met with swimming at the surface ; most of the latter be- 
7 long to the genus Salpa, and to these we will at present confine 
ur attention, Although the Salpæ are most often met with in 
_ © Warmer parts of the ocean, they are by no means confined to 
: » tropics, but have been found south of the most southern 
a point of Australia, and north of Seotland and Norway. They 
: ‘re abundant only after the water has been for some time undis- 
2 by winds, and as calms are more frequent within the 
2 ; A paper read before the Kirtland Society of Natural History of Cleveland, Ohio. 
tee upon the development of Salpa, in the Bulletin of the 
F { a $ é 
Gg Pian of Comparative Zodlogy, and were kindly Joaned for this article by Mr. 
Copyright, A. 8. PACKARD, Jr. 1876. 
