332 VERTEBKATES. 



side of the neck, just above the fore limbs. The circulation of 

 the blood in these branchial tufts can easily be seen with a micro- 

 scope of moderate power. These tufts are of a rather deeper pink 

 tinge than the remainder of the body, which is of a very pale 

 flesh-color. Exposure to light darkens the tints both of gills and 

 body. It bears some resemblance to the young of the twens, 

 which are furnished with branchial tufts, which they lose upon 

 attaining maturity, and was therefore for some time thought to be 

 the young of some unknown reptile. It has, however, been 

 proved to be a perfect animal, and has been found of all sizes. 



The blood discs of this animal are exceedingly large ; so 

 large, indeed, as almost to be distinguished by the naked eye. 

 When in captivity, its movements are slow and eel-like, nor does 

 it seem to make much use of its almost rudimentary limbs. 



It has usually been found' on the soft mud of a small lake 

 in the grotto of Maddalena. It is not always present, and has 

 been conjectured to be the inhabitant of some unknown subter- 

 ranean body of water, and to have been forced through the crevices 

 of the rocks. Besides the grotto of Maddalena at Adelsburg, 

 they have also been found at Sittich, thirty miles distant, thrown 

 up from a subterranean cavity. 



