ZOOLOGY. 573 



3481. The families of Polyps stand therefore in the 

 following order of significance : 



Fam. 1. Infusorial Polyps Tubularia. 



2. Typical Polyps Alcyoniae. 



3. Acalephan Polyps Actinia. 



Third Class. 

 Absorbent, Involucral Animals Acalephce. 



3482. The Acalephse also can only be brought under 

 three divisions, viz. Rohrenquallen, or Physalite, Rip- 

 penquallen or Heroes, Hutquallen or Medusa. 



3483. The Physalia are without doubt the lowest, 

 being only giant Infusoria ; the Beroes are allied through 

 their simple bodily cavity, to the Gorgoniae ; the Medusa, 

 through their form, to the Madrepores, especially the 

 Actiniae. 



3484. They range therefore in the following order of 

 significance : 



Farn. 1. Infusorial Acalephae Physalite. 



2. Polypary Acalephse Beroes. 



3. Typical Acalephae Medusa. 



3485. The first have not yet attained to the unity or 

 single character of the mouth, but imbibe their food 

 through numerous tubes. They are bundles of ramified 

 Vorticellse, a thoracic duct full of glands and roots, which 

 absorbs nutriment out of the sea, instead of an intestine. 



As the first family they are the antetypes of the Mus- 

 sels and Entozoa, and especially of the Hydatids and 

 Tape-worms, and we shall not be far from hitting the mark, 

 if we compare their air-bladder with the hindermost cysti- 

 form member of the body in the Hydatids. 



3486. The second family have a single mouth and 

 ribs mostly full of lamella, which are probably the ante- 

 types of gills ; they are also frequently traversed by nutri- 

 tive vessels. 



They are antetypical of Snails, being in form an 

 abdominal pouch, in substance a liver, and frequently 

 possessing paired tentacula. Higher up, and they indi- 

 cate the Crabs. 



3487. The tfrird have, as a general rule, one central 



