THALASSAECHE. 
separated by a narrow sulcus only, no soft skin being seen there. But in some 
specimens this sulcus is much more pronounced than in others, and I conclude 
that juvenile specimens will show even closer relationship than is seen in adults. 
As a second species of Thalassarche I would class D. bulleri Bothschild, which 
shows the relationship of Thalassarche and Thalassogeron culminatus even 
more plainly. In that species the bill-coloration of Th. culminatus is retained 
though the culmen towards its base spreads downwards towards th© latericorn 
and very closely resembles that of Th. melanophris. 
265 
