236 THE ZOOLOGIST. 
characteristic types, one of which was met with in spring and the 
other in winter. 
“The disappearance of the former type of Puffin just as the 
latter arrived, the presence in each of specimens evidently adult, 
the exact correspondence in size, speedily suggested that neither 
of the views above stated could be quite correct. The discovery of 
two large colonies of these birds on the coast of Brittany shortly 
strengthened my conclusion. 
“T had, in a word, arrived at the conviction that the views in 
question were erroneous, without seeing my way to a satisfactory 
solution, when a careful examination of the beak, gape and pal- 
pebral appendages led me to suspect that these parts must be 
subject to a complete metamorphosis after the breeding season. 
The more I examined the pleat (owrle/), the rosette at the base of 
the bill, the horny plates to the eyelids, the more evident did the 
metamorphosis appear. But how did this phenomenon come about? 
Was it effected only when the birds had reached the high seas, or 
was it for me to witness it in the birds which were the last to quit 
their breeding places? Of this L remained ignorant until quite 
lately. 
“In June, 1876, during a visit which I made with my brother to 
these colonies of Puffins, the examination of a large number of 
living birds strengthened my convictions, and I resolved to return 
shortly in time to witness the metamorphosis. My choice lay 
between the Ile de la Manche and the Ile de Ocean, and although 
the former was frequented by a much larger colony, I selected the 
latter in the hope of obtaining on the same rock the young of 
the Roseate Tern (Sterna Dougalli). 
“Although at that time | was occupied in Paris with my 
physiological studies, 1 started without hesitation on the 25th 
August, 1876, and on the 27th I crossed to the outskirt of the 
island, which rises above the sea in a majestic arch. But rough 
weather often prevails on this wild sea-board, abounding in shoals. 
The sea, running high with the tide and north-east wind, broke 
over the only accessible point, aud it was therefore impossible to 
think of landing; besides it would have been labour lost, for the 
rock was deserted. In the hope of finding some loiterers I explored 
in vain the shores of the island; all, old and young, had already 
taken their departure, and the Roseate Terns were also gone. My 
journey therefore was fruitless: IT had come a fortnight too late. 
a 
