An Account of the Bird-lice of the Genus Docophorus. 157 
able from D. megacephalus, D.) from Cepphus columba (Bay of Monterey, 
California), I have not, however, had an opportunity of examining 
D. procaz. 
3. While every host examined has yielded a peculiar species of 
Docophorus, “straggling” of an interesting kind is also exhibited. 
D, icterodes on A. torda and D. cordiceps on M. alle are entirely accidental. 
The former may have come from some duck or allied waterfowl, the latter 
from a wader—probably Strepsilas interpres or Tringa maritima. 
More important are the occurrences of these Docophort on Auks other 
than that to which respectively each is specially attached. One feels the 
limitations of the category “straggler” here. It has to be used so compre- 
hensively from cases of the most accidental nature to others in which 
environment and life habits play an intelligible part. 
D. merguli on UV. troile and D. megacephalus on A. torda are probably as 
unusual and casual as the two cases noted above. Yet it is not wonderful 
that such instances should occur in Shetland where, on many a day in 
January, after a gale one may see in some sheltered voe all five species of 
Auk within gunshot. 
D. calvus on Rissa tridactyla is easily understood. The Kittiwake is of 
all our gulls the most marine in habitat. It is closely associated with Alca, 
Uria and Fratercula both at the breeding season and subsequently. 
The constant mingling of Puffins, Common Guillemots and Razorbills 
—especially on the nesting ledges—is naturally reflected in the records of 
their respective Docophort. Thus U. trode has yielded D. calvus and 
D. celodoxus, while on F. arctica, D. acutipectus occurs as well. But it is 
noteworthy that D. acutipectus has been met with so far only on Puffin, and 
it is surprising that D. calvus has not occurred on Razorbill which nests side 
by side with Guillemot, so that sometimes the two species literally rub 
shoulders. Possibly a sufficient number of Razorbills has not been examined. 
The really striking feature of the occurrences of D. calvus and D. celedoxus 
is their constant attachment to one host—a fact which shows through any 
other “straggling” that may be noted. It is my impression that D. celedoxus 
has established itself on 7. arctica as well as its regular host. Buta good deal 
of collecting will be required before the status of D. celedoxus on U. troile or of 
D. calvus on F. arctica is intelligible. On Uria grylle only D. megacephalus, D., 
has occurred in my experience. More remarkable still, no other 
mallophagous species appears as a rule to infest this host. I have taken 
Menopon once on it, and on another occasion a solitary Nirmus, which is 
probably a straggler. However these facts may ultimately be explained, 
the absence of other auk Docophori on U. grylle is due probably to the 
