ACALEPHJ2. RADIATA. CYANEA. 347 



ACAL^PHJE. 



These animals are many of them familiarly known under the 

 names of Sun-fish, Sea-nettles, Sea-jellies, &c. They are of a 

 gelatinous consistency, usually transparent as glass, of a circular 

 form, and concave or umbrella-shaped. Many of them, when 

 taken in the hand, communicate a prickling sensation much like 

 the stinging of nettles, and hence they receive both their scientific 

 and their popular name. Some of them appear to capture their 

 prey by this miniature electric shock. I have repeatedly seen a 

 BE'ROE stretch out its filaments several inches until it reached a 

 crustaceous animal of nearly its own size, which, upon contact, 

 instantly fell down, either dead or paralyzed. Some of these an- 

 imals grow to a great size, and I have seen specimens of CYA'NEA, 

 on the sea-beach, a foot and a half in diameter. Others are small, 

 not more than half an inch or an inch in diameter, but all extreme- 

 ly beautiful ; and their motions, which in some of them are per- 

 formed by a process like the alternate opening and shutting of an 

 umbrella, are very graceful ; and nothing can exceed the elegance 

 of those which are propelled by little ciliae or oars arranged along 

 their sides, as in the BE'ROE. 



The larger species are found only for a short time in summer ; 

 but a great number of small species are found in cold weather, espe- 

 cially after a high wind blowing from the ocean. They evidently 

 migrate, and their course and periods are probably directed by the 

 temperature of the water, as they have no visible organs of sense. 



The forms of some of them are very beautiful, and many of 

 them would afford admirable patterns for laces and embroidery. 



The books to which I have had access enable me to determine 

 but very few species. 



CrA v NEA POSTE'LSIJ, BRANDT; Schirmquallen, 375, lab. 12, 13. 



A very large, liver-colored animal, fringed at the margin, and 

 exhibiting numerous circular bands beneath. It is found on Phil- 

 lips's and Chelsea beaches, abundantly, in August. Diameter, 

 one foot. 



