366 E. W. MACBRIDE. 
of the metamorphosis. In fig. 72 the adult mouth is formed, 
and the sessile mode of life has been given up, the stalk 
being reduced to a small solid rudiment. We see also the first 
trace of the eye as a small knob at the base of hydroccele 
lobe No. 3. Fig. 78 shows the permanent anus; if we com- 
pare its position with that which the larval anus occupied, we 
find that they are by no means the same: the larval anus, if it 
had persisted, would be situated at the point x, though both 
occupy a position on the mesentery dividing the left from the 
right posterior celoms. Fig. 77 from the same larva shows 
that the left posterior celom now forms a complete ring by 
the breaking down of the partition between its right ventral 
and right dorsal horns (U‘p’c’. and l’p’c”.). 
In fig. 73 a dorsal section, and in fig. 74 a ventral section, 
we see the incipient bifurcation of the right posterior ccelom in 
order to form the outgrowths connected with the two dorsal and 
the ventral pyloric cxca respectively. We see, therefore, that 
of the five pyloric ceca, two are formed from the dorsal end 
of the pyloric sac or larval stomach, and two from its ventral 
end, and that their suspensory mesenteries are outgrowths from 
the mesentery separating right and left posterior celoms. The 
fifth czecum is directed dorsally and posteriorly. In Pl. 22, fig. 
82, and Pl. 23, figs. 83, 84, we have three sections parallel to 
the adult plane of a specimen which had just completed the 
metamorphosis. Once the mouth is open, the trifid form of the 
adult cesophagus changes, we get the five slightly bifid lobes of 
the adult “ stomach.” In fig. 83 we see the first trace also of 
the bifurcation of the pyloric ceca; I remind the reader that 
in each arm of the adult there are two ceca; the characteristic 
appearance of the axial sinus, stone-canal, and right hydrocele 
in a section parallel to the disc are also shown, the right hydro- 
cele having a crescentic form. Fig. 84 shows us the relation 
of the rectum and the rudiment of the rectal cecum to the 
pyloric ceca; we see that the mesentery which binds the 
bases of the pyloric ceeca together is only the original mesentery 
between the right and left posterior (oral and aboral celoms) ; 
and, further, that the mesenteric band connecting the inter- 
