VIVIPAROUS FISH. 113 



to think that, a short time prior to the birth 

 of the young, sea-water has access to this mar- 

 supial sac, washes over the infant fish, the gills 

 assume their normal action, and the regular 

 systemic circle is established. Maturity at- 

 tained, the umbilical attachment snaps, and the 

 little fish, perfect in every detail of its organi- 

 sation, is launched into the deep, to brave its 

 many perils, and shift for itself. The strong 

 transverse muscles attached to the powerful 

 sphincter (constituting the genital opening act- 

 ing from the abdominal walls), I imagine, are in 

 some way concerned in admitting the sea-water, 

 and it appears to me a contrivance admirably 

 adapted to effect such a purpose; but how im- 

 pregnation takes place, I may at once honestly 

 confess I do not know. 



The male is much like the female, but more 

 slim, and the milt just like that of other fish. 

 I can only conjecture that fecundation is accom- 

 plished through the medium of the sea-water, 

 admitted by the curiously-contrived floodgate 

 of the female, carrying in the milt-germs, and 

 washing them over the ova. 



The actual period of utero-gestation I am by 

 no means sure about, but I am inclined to think 



VOL. I. I 



