4i6 



FISHES 



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. Eeferences 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, G-astrosteidae, Centrarohidae, Osphro- 

 menidae Labiidae and Antenniriidae Other illustrations of 



Fig. 237. — Showing the embryos of Rhodeus amarus in the gill-eavitie.s of Unio. e, Em- 

 bryos ; 9, iuter-lamellar cavities ; i.l.J, an inter-lamellar Junction. (FroniOlt. ) 



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 



