PARENTAL CARE AMONG FRESH-WATER FISHES. 



475 



Seba, had already described two species, to which we now add a third. All 

 three live in the waters of Guiana and this is all we know of their habits." 



Not until years later did Prof. Jeffries Wyman, of Harvard Col- 

 lege, give a true explanation of the cause of such excrescences. In an 

 able article in the American Journal of Arts and Sciences he re- 

 viewed the history of opinion and, after giving the description of 

 Valenciennes, remarked that — 



From the preceding paragraphs it does not appear that Valenciennes had 

 supposed that the so-called " cupules " were intended to contain or had con- 

 tained ova, especially as he had previously expressed the belief that the Aspre- 

 dos, in consequence of the large size of the eggs, were viviparous. The true 

 use of the api)endages in question relates to the development of the eggs, as 

 the following description will show. The habits of 

 the tish are well known to the fishern.ien, from one of 

 whom Mr. Green obtained information with regax'd 

 to their peculiar mode of gestation. After many in- 

 effectual efforts we at last succeeded in procuring 

 the specimens on which the following observations 

 were made, and Mr. Green has kindly presented to 

 me some very fine ones from his own collection, with- 

 out which this notice would have been much less 

 complete. 'J 



In the month of .June the eggs are found adhering 

 to the underside of the body, to the ventral and pec- 

 toral fins, and extend as far forward as the under 

 lip and as far backward as the middle of the tail 

 [fig. .5.0]. In some, however, the distribution is much 

 more limited. I was unable to learn anything with 

 regard to the transfer of the ova from the genital 

 orifice to the point of their attachment. The only 

 organ which seems in any way adapted to such a 

 purpose is the slender and flexible tail terminated 

 liy a delicate caudal fin. It is possible that the eggs 

 may Ite deposited on the bottom of the river and sub- 

 se(juently attached by pressing the underside of the 

 body upon them. 



In those individuals where the ova were still in the 

 ovary, but approaching maturity, the integuments of the underside of the body 

 gave no other indications of the changes about to take place than of being (piite 

 vascular. The skin was perfectly smooth, no " pores " were visible, but a large 

 vessel was seen emerging from the region of the liver, and descending along the 

 median line gave off branches quite freely to the integuments. This 'may have 

 some relation to the future development of the pedicles which support the eggs 

 and perhaps to the nutrition of the embryo as will be adverted to hereafter. 



In all the specimens which I have had an opportunity of examining, the 

 eggs were either somewhat advanced or quite mature, so that no observations 



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



6 See an account of the habits of the Aspredo by Mr. Green in the Proceedings 

 of the Boston Society of Natural History for April, 1858. [This was not pub- 

 lished.] 



Fig. 55. — Aspredo htvis, female- 

 with eggs attached to under, 

 side. 



