14 THE YOUNG OF THE CKAYFISHES ASTACUS AND CAMBARUS 



of the abdomen in such a way that the left ])as.siug posterior to the right had 

 its tip on the right side and the right jjassiug anterior to the left had its tip 

 on the left side. While all the eggs were still alive and had been kept well 

 aerated by the swaying movement of the pleopods that the mother makes, seem- 

 ingly for this purpose, yet some of them showed the effects of such a very long 

 existence in the water by being covered over upon the outside of the egg cap- 

 sule with deposits which in some cases were mixed with growths of minute 

 fungi and in some with vorticellEe. The eggs seemed under tension and burst 

 open when thrown into hot Woi'cester's liquid; the touch of a needle to the live 

 egg also caused its ca})sule to pop open. 



As seen under a pocket lens, these eggs nearly ready to hatch present a 

 most attractive ai)pearance. The carapace is spangled with branching, ver- 

 milion, pigment cells that are especially numerous along its ventral edges and 

 near the base of the abdomen, which is l)road and also well pigmented with 

 the same kind bf cell. The antenna; and antenni;les have both red and blue 

 pigment cells on their basal part, but these cells are not numerous and are 

 entirely absent from the filaments. Tiie chela; and walking legs have some few 

 scattered pigment cells. The still large dark red-brown yolk mass has the 

 forked, light-colored, "liver" projecting into it. The eyes are darkly pig- 

 mented in all their central parts, while the surface is still clear and transparent 

 for some distance inward. 



The actual hatching of the eggs took place on one female April 25-27, and 

 on another May l-(), and was prolonged over several days, that is, not all the 

 eggs on one female hatched at the same time, but whether this is normal or in- 

 duced by the artificial conditions remains to be found out from study of these 

 crayfish in their native waters. These eggs had thus required 62 to 64 days 

 in one case and 67 to 71 days in the other to develop from the well advanced 

 embryo of stages 11 and J of Reichenbach to the hatching larva. The tem- 

 perature of the water had slowly risen from 9° C. to 1-1° C. 



"When a female died before the eggs hatched, it was found possible to 

 hatch the eggs by cutting off the pleopods of the mother and fastening them 

 to pieces of floating cork so that the eggs would be suspended in well aerated 

 water. 



In hatching, the egg capsule burst open over the back of the embryo, and 

 usually opposite to the egg stalk, and then the embryo slowly glided out back- 

 ward, much in the same way as has been described for Cambarus (Andrews, 

 '04). 



In all crayfish, and in many other Crustacea, the eggs remain firmly 

 fastened to the mother during the whole period of development and when the 

 embryo escapes from tile egg-shell the old shell remains still fastened by a 

 strong stalk that is stuck to the maternal seta\ In this Astacus as the em- 



