ACALEPH^E. 



71 



Fix. 27. 



ties of sea-water, our knowledge of their internal structure is at 

 present extremely imperfect. The annexed figure of Diphyes cam- 

 panulifera (^g". 26) will give the reader a general idea of their 

 form. The two bell-shaped portions of which the creature may 

 there be seen to consist, are constantly found united together, and 

 seem to compose but one animal, although they might readily be 

 conceived to be distinct creatures ; the apex of the posterior part 

 is received into a cavity in the other portion, but the connection 

 between the two is so slight, that, when preserved in spirits at 

 least, the slightest touch is sufficient to tear them asunder ; their 

 principal bond of union appears to 

 be a delicate filament, which, arising 

 from the anterior compartment, 

 passes through the whole length 

 of the posterior portion. This 

 strange compound body, concern- 

 ing the structure of which our 

 knowledge is very imperfect, swims 

 through the water with consider- 

 able rapidity, urged forward by the 

 alternate contractions of the two 

 campanulate halves, which con- 

 tinually take in and eject the cir- 

 cumambient fluid, with sufficient 

 force to propel the creature in an 

 equable and uniform course. 



(99.) Interesting as the acalephse 

 may justly be considered when we 

 contemplate the singular beauty of 

 their external configuration, and 

 the wonderful design conspicuous in 

 their locomotive organs, a more in- 

 timate acquaintance with their habits and economy will be found to 

 disclose many facts not less curious in themselves than important in a 

 physiological point of view. In the higher animals we are accustomed 

 to find the nutritive apparatus composed of several distinct systems ; 

 one set of organs being destined to the prehension of food, another 

 to digestion, a third to the absorption of the nutritious parts of the 

 aliment, a fourth provided for its distribution to every part of the 

 body, and a fifth destined to ensure a constant exposure of the cir- 

 culating fluid to atmospherical influence. These vital operations 



