1. G. Bacci andM. La Greca, Boll. Zool.27, in print (1960).
2. U. Parenti, R. C. Accad. Lincei27, in print (1960).
3. G. Bacci et al., Exper.7, 222 (1951); R. C. Accad. Lincei28, 92 (1960).
4. G. Bacci andM. La Greca, Nature171, 1115 (1953).
5. G. Bacci, Pubbl. Staz. zool. Napoli26, 110 (1955).