Pearse, A. S., 1912. The habits of fiddler crabs. Philippine Journ. Science, VII.
—— ——, 1914. On the habits of Uca pugna and Uca pugilator. Wiscon, Acad. Sci., XVII.
Petrunkewitch, A., 1911. Sense of sight, courtship, and mating in Dugesiella hentzi, a theraphosid spider from Texas. Zool. Jahrb., Abst. Syst., XXXI.
Pocock, R. I., 1905. The effects of castration on the horns of the prongbuck. Proc. Zool. Soc., London.
Poll, H., 1909. Zur Lehre von den sekundären Sexualcharakteren. Sitz. Ges. Nat. Fr. zu Berlin.
Poncet, A., 1903. De l’influence de la castration sur le developpement du squelette. Compt. Rend. Soc. Biol., LV.
Porter, J. P., 1906. The habits, instincts and mental powers of spiders. Jour. Phys., XVII.
Potts, F. A., 1906. The modification of the sexual characters of the hermit crab caused by the parasite Peltogaster. Q. J. M. Sc., L.
Punnett, R. C., 1915. Mimicry in butterflies. Cambridge.
Punnett, R. C., and P. G. Bailey, 1914. On inheritance of weight in poultry. Journ. of Genetics, IV.