Il8 BIOLOGICAL LECTURES. 



The youngest stage among these was at the end of segmenta- 

 tion, the oldest was a gastrula covering but one-third of the 

 yolk. The eggs had not been developing more than five days, 

 probably not more than two at the utmost, and decided beyond 

 a doubt that the fish are oviparous, and not viviparous. 1 



The eggs are laid by the female in under her gill membrane. 

 Here they remain for perhaps two months, till the yolk is 

 nearly all absorbed. If at any time a female with young in 

 her gill pouches is handled, some of them are sure to escape. 

 This was observed, and gave rise to the idea that this fish is 

 viviparous. Eggs have been obtained as early as March 1 1 

 and as late as September, and the indications are that the 

 breeding season extends throughout the year. 



The eggs are translucent amber, in various shades in differ- 

 ent individuals. They are large, measuring 2.3 mm. in diam- 

 eter from membrane to membrane. The yolk measures 2 mm. 

 in diameter and contains an oil globule 1.2 mm. in diameter. 

 The globule protrudes from the yolk. The eggs are heavier 

 than water, and lie with the oil sphere uppermost and the 

 germ lateral. In one individual sixty-one eggs were found, in 

 another seventy. The exact number in the other two I cannot 

 give, but the number does not differ greatly from the above. 

 From one side of one I took thirty-five eggs, from the other 

 individual an uncertain number. The remaining eggs were 

 left in the gills to develop, but all those that were not subse- 

 quently preserved finally died. 



The female with eggs can readily be distinguished by her 

 distended gills, and since dead eggs become opaque, such can 

 readily be distinguished through the translucent opercles and 

 branchiostegals. Dead eggs are retained in the gill cavity till 

 they disintegrate. 



I have never secured as many young from any female as eggs 

 enumerated above. This may have been either on account of 

 the dying of many eggs or the liberation of the young during 

 the struggle of capture. 



1 This is the first of a series of embryos obtained through a grant of $100 

 from the Elizabeth Thompson Science Fund, made to enable me to continue my 

 work on the blind-fishes. 



