THE DEVELOPMENT OF ASTERINA GIBBOSA. 405 
Fics. 62—69.—Hight sections of a larva slightly older than Stage F, to 
show the relation of the arm rudiments to the lobes of the hydroccele. Fig. 68 
shows the incipient healing of the breach in the septum between the anterior 
ccelom (axial sinus) and the left posterior ceelom. Figs. 64 and 65 show that 
arm rudiment No. V is still widely separated from hydroccele lobe 1 by the 
base of the stalk, and also that the right ventral horn (/'p'c!.) of the left 
posterior ccelom is not completely separated from the axial sinus (a’.). Fig. 
65 also shows the complete separation of the hydroccele from the axial sinus. 
Figs. 66 and 67 show relation of the oral ecelom (07. c.) to the adult cesopha- 
gus (a. @.). Fig. 69 shows the adhesive disc of the stalk (jiz.) attached toa 
piece of Alga (x), and the rest of the ectoderm of the preoral lobe being 
invaginated (Azs¢.) to undergo destruction. It also shows that each primary 
lobe of the hydroccele has developed two pairs of secondary lobes. 
PLATE 22. 
The same remarks apply to Figs. 70—78 as to the contents of the three 
foregoing plates. Figs. 79—82 are sections cut parallel to the dise of the 
star-fish or ‘‘adult plane,” the magnification being the same, viz. 80 dia- 
meters. 
Fies. 70 and 71.—Two sections of a larva of Stage G. Fig. 70 shows the 
relationship which the adult and the larval cesophagus occupy with regard to 
one another, the latter being a mere rudiment unconnected with the gut ; it 
also shows the outgrowths from the adult cesophagus. Fig. 71 shows the 
oral ccelom opening into left posterior ccelom ventrally by breaking down of 
partition between them; also the first trace of the pyloric ceca as outgrowths 
from the pyloric sac. 
Fic. 72.—Section of larva rather older than Stage G. The adult mouth is 
formed, and the oral ccelom opens widely into the left posterior celom. The 
stalk has become a small solid rudiment. The dotted line shows the boundary 
between the pyloric sac and the adult ‘‘ esophagus” or “‘ stomach.” 
Fic. 73.—Section of a larva of the same age as the preceding; it shows the 
two dorsal pyloric cxca already formed, also the so-called heart or “ovoid 
gland” (ovg.), as a fold projecting into the axial sinus (a’.). 
Fic. 74.—Another section from the same series as Fig. 72. Shows the two 
ventral pyloric ceca; it is seen also that their suspensory mesenteries are 
derived from the mesentery separating the right posterior ccelom from the left 
(compare Fig. 75). Note also that the tube-feet have acquired their suckers, 
The animal has broken loose from its attachment, which accounts for the 
rudimentary condition of the stalk. 
Fie. 75.—A section of a larva of Stage G. Shows the dorsal pyloric ceca 
and their suspensory mesenteries. 
Fig. 76.—A section of another larva of Stage G. Compare with Pl. IV, 
fig. 61, and note that the arm rudiment No. V (not marked in the figure) has 
