Note 10 — Chapter I · VOYAGE FROM NEW YORK TO RIO DE JANEIRO.

In copying the journal from which these notes are taken, I have hesitated to burden the narrative with anatomical details. But for those who take an interest in such investigations it may be well to add here that the frog, when first hatched, is simply an oblong body, without any appendages, and tapering slightly towards its posterior end. In that condition it resembles the Cecilia. In its next stage, that of the tadpole, when the extremity has elongated into a tail, the gills are fairly developed, and it has one pair of imperfect legs, it resembles the Siren, with its rudimentary limbs. In its succeeding stages, when the same animal has two pairs of legs and a fin around the tail, it recalls the Proteus and Menobranchus. Finally the gills are suppressed, the animal breathes through lungs, but the tail still remains; it then recalls Menopoma and the Salamanders. At last the tail shrinks and disappears, and the frog is complete. This gives us a standard by which the relative position of the leading groups of the class may safely be determined.—L. A.