416 THE AQUARIAN NATURALIST. 



may be traced mounting upwards along the oesophagus 

 to terminate by a distinct orifice, situated close to the 

 outer side of the tentacular ring. Thus, instead of 

 being a simple bag, as in the Hydriform Zoophytes, 

 the alimentary canal consists of pharynx or oesophagus, 

 gizzard, stomach and intestine, all of which float freely 

 in a visceral cavity formed by the delicate, transparent 

 parietes of the animal, and apparently occupied by a 

 clear fluid, wherein are lodged the delicate muscles 

 that serve for the retraction of the creature. 



The most ordinary mode of reproduction in the 

 Polvzoa is by a process of gemmation, or budding 

 from the common polypary or creeping stem, on which 

 young animals in various stages of growth may always 

 be seen, sprouting from the parent-stock (PL VII. 

 fig. 7), and in these the nascent polyps may readily 

 be witnessed through the transparent walls of their 



cells 



" timidly expanding into life," 



while the growth of their various organs can be traced 

 from hour to hour, until they burst forth, and begin to 

 exercise the functions peculiar to their species. 



The Polyzoa generally are amongst the hardiest 

 and most easily reared occupants of the aquarium. 

 The Rev. Mr. Hincks observes, that he transported 

 specimens from the coast of Lancashire to Exeter, a 

 distance of three hundred miles ; and although he was 

 unable to renew the water in which they were kept, 

 they continued to live, after their long journey, for 

 two or three days. " At the end of that time they 

 showed signs of a disposition to get rid of their heads 

 which is by no means a suicidal act in a Pedicellina, 



