REV. T. RIDDELL ON THE BALANUS. 



195 



Mean barometric height at the level ) ., t t <i- i- 



of the sea^29.82 inches, ) ° 



Log. 29.286 =1.4667 



.0078 



1000.0. 



Height of the place of observation must be , 

 somewhere about ' 



78 fathoms, or 468 ft. 



On the Metamorphosis of the Balnniis ptmctafus of Montagu. By the 

 Eev. T. EiDDELL, Fellow of Trinity College, Cambridge. 



Among all the facts recently brought to light in Animal History, 

 there is, perhaps, none more wonderful than the discovery made by 

 Mr Vaughan Thompson, and published in his Zoological Researches, 

 respecting the transformation of the Balani. An account of Mr T.'s 

 observations, together with a statement of the opinions of several 

 eminent naturalists respecting the correctness of his views, may be 

 found in the Penny Cyclopaedia, Art. Cirripeda. That an animal 

 should be furnished, in the first stage of its existence, with organs of 

 motion and swim about freely like a shrimp, and afterwards become 

 immovably fixed to a rock and clothed with a hard stony shell, seems 

 at first sight so highly improbable, that persons might be expected to 

 suspend their belief till the fact should be fully proved. 



Having heard from Dr Johnston in the beginning of June that he 

 had found Balani in all their stages, near the mouth of the river at the 

 fishing bat opposite Spittal, I went down the first favourable day to 

 the place he had mentioned, and succeeded in obtaining several of the 

 animals in the earliest stage of their growth, as described by Mr 

 Thompson. They were spread in countless numbers over the stones, 

 but none of them were free ; all were found adhering, seemingly by a 

 short fine pedicle or stalk, to some object, either stone, shell, or sea- 



