416 FISHES CHAP. 
surface of the shell. The male remains on guard, and by the 
movements of its pectoral fins promotes the aeration of this rude 
form of nest. References to some of the more striking examples 
of true nest-building in Fishes will be found in the systematic 
part of this volume, especially in those chapters treating of the 
Dipnoi and Amiidae, and such Teleosts as the Mormyridae, 
Osteoglossidae, Siluridae, Gastrosteidae, Centrarchidae, Osphro- 
menidae, Labridae, and Antennariidae. Other illustrations of 
i> | 
(a 
Fic. 237.—Showing the embryos of Rhodews amarus in the gill-cavities of Unio. e, Em- 
bryos; g, inter-lamellar cavities ; 7.7.7, an inter-lamellar junction. (From Olt.) 
parental care are to be found in the development of mar- 
supial pouches or grooves for the reception of the eggs in the 
males of the Syngnathidae (Fig. 387) and the females of the 
Solenostomidae, and the use of the oral cavity for a similar 
purpose in the males, rarely in the females, of some Siluridae, 
and the males or females, according to the species, of the 
Cichlidae. The singular method by which the female Aspredo 
safeguards both her eggs and her progeny is referred to on 
p. 596. The Cyprinoid, Rhodeus amarus (the “ Bitterling” of 
Central Europe), is unique in the means which it adopts to 
