240 VIVIPAROUS BT/ENNY. 



The males are much less in number than the females, and 

 are also of inferior size; but they are not otherwise to be 

 distinguished, except when the females are distended with the 

 young. \Villoughby supposes the season of fertility to be 

 about the spring equinox, but according to Xilsson it is through 

 the year; at which time the grains of spawn are very small, 

 firm, and of a whitish colour; and they are seen to be con- 

 tained in a bag which before had appeared empty. In a little 

 more than a month these grains have increased in size, and 

 are become of a reddish colour; they become more soft when 

 as large as a grain of mustard seed, and then they assume a 

 lengthened shape, with a couple of dark specks where the eyes 

 are to be. The thread also is visible by which the nourishment 

 is conveyed into the bowel; and finally the tail is seen, but not 

 thicker than a very slender thread, and it appears bent at its 

 termination. With the growth of the young the belly of the 

 parent becomes more and more distended, but not solely from 

 their increasing bulk; for what contributes to it is a tenacious 

 fluid with which each ovum is supplied, and by which (and 

 an attendant bed of soft fibres) the soft and tender substance 

 of each young one is kept from pressing on and injuring the 

 structure of the others. The thick and tenacious fluid in which 

 the young ones float diminishes as their growth increases, and 

 it altogether disappears about the time when they are to be 

 produced to light, no doubt by absorption into the body, the 

 number at one birth having been known to amount to three 

 hundred. This would appear, however, to be the extreme limit 

 of their number, since Nilsson says that in a fish which measured 

 a foot in length, it amounted to one hundred and ninetv-five, 

 and in one of thirteen inches to two hundred and sixty-two. 

 It breeds at an early age, since a fish which measured only 

 six inches has been known to contain roe; but the number 

 produced, and their size, have been observed to vary with the 

 bulk and consequent age of the parent; so that the example 

 from which our figure and description were taken, and which 

 was a little beyond ten inches long, produced only seventy, 

 while in some of the largest size the young ones in this first 

 stage of their existence, measured between four and five inches; 

 and so perfect are they at their first entrance into life, that 

 they are immediately able to put forth all the activity of exis- 



