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Show 242 MR. G. E. DOBSON ON SECONDARY SEXUAL [Mar. 4, like elevation on each side is enormously developed, forming a large callosity, extending forwards in front of the eye, and backwards to the posterior margin of the opening of the frontal sac. These, with the raised and swollen margins of the opening of the frontal sac, form on the forehead a naked, livid, triangular space, extending from the transverse nose-leaf backwards between the ears. The adult female possesses, as in other species, a very rudimentary sac, placed close behind the transverse nose-leaf; and the small wart-like elevations on either side are almost concealed by the hair of the forehead. Fig. 1. Fig. 2. S ? Phyllorhina armigera. The drawings well represent the relative development of the parts referred to above in the male and female P. armigera. The original drawings have been made from specimens in the Indian Museum. I have observed a similar development of these glandular prominences in an adult male specimen of P. larvata, Horsfield, from Assam ; but in all other apparently adult specimens of this species in the Indian Museum they are not larger than in other species of Phyllorhina. The question therefore arises whether this enlargement of the glandular elevations, with proportional development of the frontal sinus in the male, depends on season, or on the age of the individual, or on both. Mr. Blyth remarks, in a footnote, on the frontal sinus of Bats of this genus (Journ. As. Soc. Beng. vol. xiii. p. 487): - "It is probable that the development of this sinus, and also of the throat-sac of the Taphozoi, depends much on season, like the infraorbital cavities of various ruminants and analogous glandulous follicles in many other animals." The development of the frontal sinus and glandular prominences being primarily a sexual character, I believe that the relative development of these parts among males of the same species is dependent on both age and season. I have always found the frontal sac in aged individuals greatly developed; the development of the |