800 
ALCAD^. 
coaxing one of them quite close up to me by gently tossing 
pebbles in front of it. 
The only opportunity I ever enjoyed of seeing Black Guille- 
mots travelling under water at what may be supposed their full 
speed, occurred one afternoon in February, I was standing 
upon a rock near the foot of a low cliff, upon the other side 
of which repeated firing could be heard, when Ty sties, con- 
spicuous in their gTey winter plumage, came sweeping round 
the point, literally flying under water, seemingly intending to 
take refuge in the little bay ; but having observed an unavoid- 
able movement on my part, with one accord they rose and 
flew rapidly away. 
The changes of plumage occurring among the various species 
of sea birds have always been most difiicult to thoroughly in- 
vestigate, but among certain families, the Divers and Guillemots 
for example, the extraordinary liability of certain individuals 
to retain the summer plumage until winter, and of others to 
assume it many weeks before the accustomed time in spring, 
has led, and still leads, to a vast amount of perplexity. To 
take the Eed-throated Diver as an instance. As long as it 
occurs in winter plumage during the recognised period, the 
summer and ^^inter dresses are believed to be quite distinct ; 
but no sooner is a chance specimen procured, late in autumn 
or very early in spring, exhibiting a red throat, than the pos- 
sessor — who probably is scarcely so well up in his “ Zoologist” 
as he ought to be — immediately revives the old question, and 
for a while the pages of our natural history journals are encum- 
bered with the discussion of a matter which has long since 
been satisfactorily settled. Nearly every ornithologist now 
admits that the Common Guillemot loses the black throat in 
winter, yet rare exceptions do occur ; * and because similar 
abnormalities are observed more frequently in the Black 
Guillemot, which is exceedingly common at all seasons, it has 
* l have met with instances in December and January, In making such 
assertions as the above, the month should invariably be mentioned, to avoid 
the danger of trusting to memory, and thus ]>erhaps committing the grave 
errop of speaking of a snowy day in October or April as “the winter time.” 
