METAMORPHOSIS OF " SPINTJLA." 449 



metamorphosis whereby this is effected, we are in- 

 debted to Sir John Dalyell; and consequently, al- 

 though later researches have since filled up the out- 

 lines of his description with many elaborate details, 

 we shall lay before the reader the original sketch, 

 which may well serve as a model for the observant 

 naturalist : 



" Having obtained a quantity of heterogeneous 

 collections from the sea about the middle of summer," 

 says Sir J. Dalyell, " I discovered for the first time a 

 minute reddish animal, nearly a line in length, re- 

 sembling a common pin, such as is used in apparel, 

 which was endowed with considerable activity. It 

 disappeared suddenly without exciting much surprise ; 

 however, for the purpose of recognition, a rude draw- 

 ing had been made of it, and it was denominated 

 ' Spinula' from its peculiar shape. 



" Exactly five years afterwards, a similar animal 

 again made its appearance ; and it was with some sur- 

 prise that I found this to be precisely on the same day 

 of the year, the 19th of July. The coincidence being 

 remarkable, demanded more sedulous attention. I 

 acknowledge that I felt rather disposed to consider 

 the object an early stage of some foliaceous or car- 

 nose Zoophyte, than as pertaining to anything else, 

 providing it were not itself a perfect animal." 



The " Spinula " bears the strongest resemblance to 

 the shape of a common tadpole. A large head, 

 almost opaque, with a black internal speck, declines 

 into an attenuated flattened tail, by the aid of which 

 it wriggles through the water. There was in another 

 tank a whole colony of these Spinnta, and many were 



