78 AMPHIBIA. 
lungs, and in undergoing consequently a total change im 
the medium of their respiration; whilst the Protews and 
the Siren retain their branchie with lungs, (tudimentary, 
at least,) and probably throughout life possess synchro- 
nously the two-fold function of aquatic and atmospheric 
respiration. The Amphiuma and Menopoma have not as 
vet been observed to possess branchie at any period of 
their existence, though further observations are necessary 
to warrant the conclusion of the absolute non-existence 
of a metamorphosis in those genera.” * 
As it appeared to me that no one arrangement hitherto 
given had sufficiently distinguished the different forms, I 
proposed, in the article just quoted, the following modifica- 
tions as more consistent with the diversities of structure in 
the different groups. 
Crass AMPHIBIA. 
Order I. anoura. 
Body short and broad. Feet during the tadpole state 
wanting; afterwards four, the hinder ones long, and 
formed for leaping. Tail before the metamorphosis long, 
compressed ; afterwards totally wanting. Ribs wanting’ 
Vertebree few and anchylosed. Tympanum open. Respi- 
ration at first aquatic by branchie, afterwards atmospheric 
by lungs. Branchie at first external, but withdrawn with- - 
in the chest before the metamorphosis, Impregnation ef- 
fected externally during the passage of the ova. 
Genera. Lana, Hyla, Bufo, &c. 
* See the article “ Amphibia,” by the author of the present work in Dr. 
Todd’s Cyclopedia of Anatomy and Physiology. 
