4 POPULAR BRITISH CONCHOLOGY. 



Of the Compound Ascidians, or BotryUida, in which a 

 number of animals group together, so as to form one com- 

 pact mass enclosed in one bag, I may give two instances : — 

 First, the AplicUum fallax (PL I. fig. 3), which looks like 

 an irregularly shaped bag fastened down at the open end, 

 and is found on examination to contain a number of indivi- 

 duals placed in a circular row within the mass : eacli indi- 

 vidual has a mouth, with a six-rayed breathing apparatus, 

 and each an opening for ejection. Then, a Botryllus {B, 

 poli/ci/clus, PL I. fig. 6) is beautifully described in a letter by 

 Dr. Schlosser, published in the ' Philosophical Transactions' 

 nearly a hundred years since, an extract from which may 

 give some idea of the pleasurable excitement attending the 

 intelligent pursuit of nature. " The first time the fishermen 

 hauled in the dredge, I discovered a most extraordinary sea 

 production surrounding the stem of an old fucus ; it was of 

 a hardish but fleshy substance, and more than an inch thick, 

 of a light brown or ash colour, and the whole surface was 

 covered over with bright yellow shining and star-like bodies, 

 which induced me to believe it to be an uudescribed species 

 oi Alci/onum. I put it immediately into a basket of sea- 

 water, expecting every moment the polypes, which I thought 

 were lodged in these little stars, would extend and show 



