NATURAL HISTORY OF AMIA CALVA LINNAEUS. 107 



(Carbonnier, '75), and two in which the male constructs a nest of mucous-coated 

 air-bubbles, Poly acanthus viridi-auratus (Carbonnier, '69) and Osphromenus gou- 

 ramy (Carbonnier, '76). In these four instances the male continues his care for some 

 time after the eggs are hatched. 



In addition to these twenty cases there are others in which nests are known, but 

 in which the time and method of building them appear to be unknown (see Budgett, 

 :01, and Kerr, :00). 



That in the cases cited the male rather than the female builds the nest and 

 subsequently guards it and the young brood, is made clearer by three considerations : 

 first, that, since fertilization is external, both fish are necessarily present when the 

 eggs are laid; secondly, that the eggs of a single female are laid within a relatively 

 brief time; and thirdly, that of the two parents the male is the more active and 

 has not been weakened by the bringing to maturity of a great mass of eggs. That 

 the habit of guarding the nest and young has been developed in the male rather 

 than the female is no doubt correlated with these facts. If the fertilization were 

 internal so as to make the presence of the male unnecessary when the eggs are laid, 

 and if at the same time the eggs were larger and produced singly, and the egg- 

 laying extended over several days, then the brooding habit might develop in the 

 female rather than in the male. 



The condition found in Ameiurus and Crenilabrus, in which the female works 

 with the male, although she alone is never the nest-builder, is then exceptional. It 

 may be regarded as a case of transference of male characters to the female, such as, 

 in the opinion of Darwin ('83), has taken place in respect to the colors of certain 

 brightly colored female fish. 



IV. LITERATURE. 



Agassiz, L. 



'57. [Fishes of Greece.] Proc. Amer. Acad. Arts. Sci., vol. 3, pp. 325-333. 



Arnold, I. 



'83. Successful Propagation of Black Bass. Bull. U. S. Fish Comm. for 1882, vol. 2, pp. 113-115. 



Bream, A. E. 



'92. Thierleben. Aufl. 3, Bd. 8, Die Fische. Leipzig u. Wien, 8°, xviii+517 pp., 1 Karte, 11 Taf. 



Budgett, J. S. 



:01. On the Breeding Habits of some West-African Fishes, with an Account of the External Features in 

 Development of Protopterus annectens, and a Description of the Larva of Polypterus lapradei. 

 Trans. Zool. Soc. London, vol. 16, pt. 2, pp. 115-134, pis. 10-11. 



Carbonnier, P. 



'69. Sur le mode de reproduction d'une espece de poissons de la Chine. C. R. Acad. Sci. Paris, vol. 69. 

 pp. 489-491. 



