150 THE DEVELOPMENT OF 



such or not. The pigment of the compound eye is first 

 deposited in a linear patch (fig. 18, ey). In this stage 

 the yolk is much less abundant than in the previous one. 



The changes which occur between stages .Fand G (fig. 

 20) are chiefly those of degree. The yolk is less extensive, 

 the edge of the carapax is free all around, the eye has more 

 pigment and pigment spots are visible upon the sides and 

 on the antennulse. In the abdomen the ganglia are plainly 

 visible (?ia) and the telson {vide fig. 22) is bifurcate and 

 armed with the typical seven spines on either half. The 

 anterior end of the intestine terminates in a wide open fun- 

 nel which spreads to embrace the yolk and the whole tube 

 keeps up a constant peristaltic motion which forces the yolk 

 granules in the funnel-like extremity back and forth with 

 an oscillating motion. The heart beats as rapidly and 

 more vigorously than before. Its general appearance is 

 shown drawn to a larger scale in fig. 21. A detailed de- 

 scription of it will be given later. 



Stage H (fig. 23) is the young shrimp nearly ready to 

 hatch. The abdomen has now become greatly longer and 

 is wrapped around the body, its tip passing between the 

 eyes to the front of the head. The yolk is greatly re- 

 duced, two large lobes of it remaining in an unbroken con- 

 dition while another portion is being rapidly converted 

 into yolk globules by the waves caused by the peristaltic 

 action of the intestine. The heart is larger and more vig- 

 orous than before. It still possesses but two ostia (one 

 on either side) but a new feature is seen in the appearance 

 of bipolar nerve-cells in its walls. I have not been able 

 to trace the origin of these cells. The gills are beginning 

 to bud from the bases of the limbs as small lobes. The 

 mouth-parts (figs. 24, 25, 26) are well shown in the draw- 

 ings and call for but little comment. The mandible, how- 

 ever, has one feature which should be mentioned. In the 



