128 Proceedings Of united states national museum, [isss. 



ON THE DEVELOPMENT OP VIVIPAROUS OSSEOUS PISHES. 

 By jrOHlV A. IRITDER. 



INTRODUCTORY. 



The following paper is intended to give a summary of our knowledge 

 respecting the best known of the truly viviparous osseous fishes char- 

 acterized by an intrafoUicular or intraovarian development. The only 

 memoirs of importance which have not been consulted in the prepara- 

 tion of this series of notes is that by Rathke,* on Zoarces vivi^arus, and 

 that by Duvernoy on Pcecilia surinamensis, which is cited at another 

 place. 



The preliminary notice published by me on the development of Gam- 

 l)usia appeared nearly four years ago, and left the subject in a very 

 incomplete state. What is here added on the anatomy of the embryos 

 and the follicles may, I trust, be of interest to morphologists. 



The new observations here recorded on the changes undergone by 

 the embryos of the Ebiotocoids during gestation, relate to the devel- 

 opment of the intestine and the vascular supply of the median fins, 

 both of these organs also undergoing other changes which have appeared 

 to the writer to have considerable significance. 



Some apology may be necessary for the long extracts which I have 

 incorporated from the paper by Professor Wyman and Dr. Girard's re- 

 port, but I think the student who wishes to be spared the vexatious 

 task of finding and consulting authorities will be rather gratified than 

 'Otherwise to find the American contributions to the subject thus brought 

 together. 



I.— The development of Anableps. 



Wy man's memoir t on Anableps contains such valuable observations 

 and reflections on the viviparity of fishes that I will here reproduce the 

 most important parts of his paper entire, as follows : 



" Extended observations have proved that a large number of species 

 of fishes, belonging to many genera, are truly viviparous, the foetus 

 passing through a real gestation by the parent before its development 

 is complete. These viviparous fishes may be divided into two groups, 

 according to the position occupied by the embryo during the period of 

 its growth. 



"I. In the first group may be arranged those fishes in which the 



* Bikliings- und Eutwickeluugsgeschicbte des Bleunius viviparus oderdes Scbleim- 

 liscbes. Abbaudl. zur Eutwickelungsgeschiclite. Zweiter Tbeil, Erste Abb.,pp. 1-68 

 )d.s. 5, 4to, Leipsic, 1833. 



t Observatious ou tbe developmeut of Anableps Groncvii (Cuv. & VaL). By Jeffries 

 Wyiuau, M. D., Boat. Jouiii. Nat. Hist, vi, 1850-57, pp. 432-443, pb xvii. 



