596 TELEOSTEI chap, xxi 



Fam. 6. Aspredinidae. — This family is also closely related 

 to the Siluridae. The ribs are sessile as in the Loricariidae, but 

 inserted very low down on the centra, which higher up bear 

 strong transverse processes. The opercular bone. is entirely absent. 

 The gill-opening is reduced to a foramen in front of the pectoral 

 fin. The head is extremely depressed and the mouth terminal ; 

 the tail is very slender ; the body is naked. The air-bladder is 

 large and free, the intestinal canal short. Four genera from 

 South America : Asjn'edo, Bunocephcdus, Bimocej)hcilic]ithys, 

 Bysichthys. Species 18. Asjjredo, of the Guianas, the largest 

 form, reaching to about a foot in length, is remarkable for the 

 manner in which the female carries her eggs. The skin of the 

 lower parts assumes a spongy condition about the breeding 

 season, and the eggs, after being deposited, become attached to 

 the lower surface of the head, belly, and paired fins, forming a 

 single layer ; each egg becomes connected with the skin of the 

 mother by a cup-shaped, pedunculate base, supplied with blood- 

 vessels and coated with a layer of epithelium, the formation of 

 which is still unexplained.^ 



^ Cf. ^Vyman, Amer. Journ. Sci. (2) xxvii. 1859, p. 9, and Vaillant, C R.Ac. Sci. 

 c.x.xvi. 1898, p. 544. 



