oA 0) TUNICATA.—SALPADA. 
that such constantly solitary Salpe did not belong 
to species distinct from those united in chains, 
however dissimilar (and they are so dissimilar 
usually, as to appear even generically distinct), 
but were either the parents or the progeny, as the 
case might be, of the aggregate forms; that chained 
Salpe did not produce chained Salpe, but solitary 
Salpe, which, in their turn, did not produce solitary 
beings, but chained. Cansequently, as Chamisso 
graphically observes, ‘a Salpa mother is not like 
its daughter or its own mother, but resembles its 
sister, its grandaughter, and its grandmother.’” * 
More recent researches have fully confirmed the 
correctness of these observations, strange as they 
at first appeared. Nor are the facts so singular as 
they were then believed to be; for the same law 
(now known as that of the Alternation of Genera- 
tions), has been found to prevail extensively in the 
Meduse and Hydroid Polypes. 
One or more species of this genus have been at 
various times observed in the seas which wash the 
British coasts; and the first detection of the genus 
we owe to the eminent geologist, Dr. McCulloch. 
His graphic description of the discovery is so in- 
teresting, that I shall give it with a slight abridge- 
ment, though it repeats some details already 
mentioned. The. species was probably Salpa 
runcinata. } 
“Some marine animals occur in these seas 
which remain still unrecorded in the catalogue of 
British zoology. Among these, indeed, it is pro- 
bable that a few will be found still undescribed by 
naturalists, since fresh additions are even yet 
occasionally made to our catalogue of these ob- 
* Brit. Moll. i. 47. 
