1'4C. VvoL M'Iiitosir.s Xotes from the 



luxviiig muscular fibres from the bristle-tuft attached to it; 

 aud the hypoderm is thiuucd at the tuft aud has au incurva- 

 tion at its upper edge, whilst it rapidly thickens above it. 

 ^Moreover, a distinct muscular slip {inc.} occurs in the mid- 

 ventral line, the remnant of tlie complex condition in front. 



Tiie next change is the infolding of the stomachal wall 

 (PI. Vlll. fig. 10, 5/.), the loss of its lateral connections, and 

 the termination of its cavity ; whilst the intestine enlarges, 

 its folds become more prominent aud alter their character, 

 resembling, indeed, the oesophageal hypodermic lining. The 

 intestine still shows a plexus of vessels, about seven, for 

 instance, being cut on eaeli side, and they resemble buds 

 from the investment of the gut, though they are only sections 

 of longitudinal trunks with their internal and external 

 investments. The dorsal mesentery and its enclosed vessel 

 now pass upward from the gut-wall, and inferiorly are the 

 veutral mesentery aud its vessel, the membrane trending to 

 a fissure between the more massive veutral longitudinal 

 muscles, since the special median muscular area and its fibres 

 (shown in PI. "S'ill. fig. 7 a) liave disappeared. The nerve- 

 cords are separated only by their own breadth from each 

 other, and they are, perhaps, more distinctly granular than 

 before. The mucous glands, with their secretion rendered 

 fibroid by preparation, are now prominent, each placed 

 above the ventral muscle of its side. The coelomic S])aces 

 (PL IX. Hg. 11, c), reduced to one on each side, have a 

 translucent coagulum with granules. 



When the nerve-cords touch and fuse (PI. IX. fig. 11, 7ic.) 

 it is seen that the glandular tubes in the ccelom approaeli 

 each side of the ventral vessel, and slope outward as they go 

 forward to the excretory duct below the bristle-tuft. The 

 gut has become pear-shaped, the narrow end being below 

 with its mesentery, whilst two mesenteries pass from the 

 dorsal arch and join before reaching the dorsal blood-vessel. 

 This arrangement makes an additional sujira-iutestinal 

 chamber. 



The hypoderm still presents a symmetrical enlargement 

 just above the bristle-tuft on each side, this thickened region 

 being difl'erentiated by the narrow layer immediately above 

 it, for it gradually deepens dorsally and again becomes 

 narrow as it reaches the mid-dorsal line. From the lower 

 edge of the bristle-tuft it gently increases to the nerve-cords 

 in the mid-ventral line. The dorsal longitudinal muscles 

 are thinner than the massive ventral, but they extend over 

 a larger area of the body-wall. 



A little fuither back (PI. IX. fig. 12) the gut increases ii; 



