58 ANATOMY OF AMPHIOXUS. 



region of the twenty-seventh myotome, where the pharynx 

 ends and the intestine begins. They were discovered in 

 1875 by LANKESTER, who called them the atrio-ccelomic or 

 brown funnels, on account of the rich accumulation of 

 brown pigment in their walls. We have already referred 

 to this brown pigment as occurring very generally in the 

 atrial epithelium. The brown funnels have the shape of an 



<?0 



Fig. 28. Plastic diagram illustrating the positions and relations of the atrio- 

 coelomic funnels. A rod is passed through the peri-enteric coslom into the sub- 

 chordal (suprapharyngeal) coelom. (After LANKESTER.) 



ao. Dorsal aortas, at. Atrial cavity, b.f. Atrio-coslomic funnels, go. Gonads. 

 l.d. Ligamentum denticulatum (pharyngo-pleural folds, Lankester). l.m. and 

 r.m. Left and right metapleural folds. my. Muscles. pfi. Roof of pharynx. 

 u. Point of union of the right and left aorta? into the median aorta. 



elongated cone, the apex of which is directed forwards. 

 At the wide end each funnel opens into the atrial cavity, 

 while at the narrow end it is possible, but not certain, that 

 an opening exists into the dorsal coelom (Fig. 28). The 

 funnels are adherent throughout their entire length to the 

 roof of the dorsal ccelom. 4 



