158 Proceedings of the Royal Physical Society. 
habits of the bird. It is an inshore feeder, breeds not on ledges but in 
holes, crevices, or under boulders, and, except under stress of weather, does 
not associate closely with other Auks. Possibly a similar explanation may 
hold of J. alle, which likewise has one Docophorws invariably present. The 
Little Auk, however, harbours a Nirmus and a Menopon as well. 
D. merguli, D., and D. megacephalus, D., have important structural features 
in common, notwithstanding some superficial dissimilarity, and are somewhat 
apart from D. acutipectus, K., D. calvus, D., and D. celedoxus, N., which form a 
compact group. All five species may however be treated conveniently 
together, and this I hope to do in a later instalment dealing with the 
distinguishing features of the species and their known distribution in 
Britain. 
(Issued separately, 27th June 1914.) 
