474 



PAEENTAL CAKE AMONG FRESH-WATER FISHES. 



forepart of the back are much depressed; the usual opercular bones 

 are present, but rudimentary; the mouth is inferior; the intermaxil- 

 lary bones are remarkable for being placed in a longitudinal instead 

 of transverse direction ; the unarmed dorsal is far forward ; the pec- 

 torals are horizontal and each armed with a very strong spine. Only 

 a couple of dozen of species are known. A special interest attaclies to 

 species of this family on account of the very peculiar care taken of 

 their eggs by some of the species at least. 



In all the other Nematognaths, so far as known, the care of eggs 

 and young is devolved chiefly if not entirely on the male parent, but 

 those Aspredinids whose gestation is knoAvn (and that of four species 

 is) act quite differently and in a very remarkable manner. 



As long ago as the eighteenth century representatives of the family 

 had been described with small globular bodies pendant from the 

 breast and those were supposed to be distinctive of a species named 

 therefore Asjrredo cotyleplioynis ; their function was unknown and 

 not even guessed at. Not rmtil nearly a century later were they recog- 

 nized as eggs. 



Even the great and learned ichthyologist Valenciennes had no con- 

 ception of their true nature. As late as 1842, in his chapter on the 

 genus Aspredo, he wrote as follows : 



A certain number of individuals in each species (of Aspredo) are reniarli- 

 able for singular appendages on the underside of the thorax and abdomen, 

 and which, after the few observations which I have been able to make, appear 

 to indicate a certain state of the female. I have not seen them in the males and 



I'ic. 54. — Afiprcdo filamentosus. After Valeccienues. 



the females do not have them at all times. They first appear as pores on the 

 under and naked surface of the trunk : and these enlarge and swell into tubei-- 

 cles, which subsequently elongate into filaments, and the extremity of each 

 filament is dilated into a small cupule." 



It was in this state that Bloch saw them in an individual with six cirrhi. and, 

 taking them for specific characters, named the fish Platystacus cotylophorus. 

 But I have seen the same appendages in three species. Artedi, in the text of 



o Cuvier and Valenciennes, Hist. Nat. des Poissons, T. XV, p. 430. 



