PLATE 12. 

 Pectin, atella magsifica Leidy. 

 Fig. l.# Front view of a polypide nmch enlarged, with the arms re- 

 moved, showing the under side of the lophophore. (Norway, Me.) E, en- 

 docyst; B, invaginated fold; H', tubular base of the tentacles; Z, clear 

 spaces in the endocyst ; L ', brachial contractors ; M, position of the lopho- 

 phoric flexor ; I ', outline of the epistome ; S, nerve mass ; T, lophophorie 

 nerve trunks ; T ", brachial nerve trunks ; T '", polypidal nerve trunks ; K, 

 oesophagus; K'", cesophagal valve; K', stomach; K "", intestinal valve; 

 K ", intestine ; K, anus ; M ', lophophorie retractor ; M ",' brachial retrac- 

 tors; F, brachial collar; N, anterior retentors; N', posterior retentors. 



Fig. 2. Lateral view of a portion of the inside of one of the arms, 

 showing the fibres of the inner and outer tentacular bands. H, bases of the 

 tentacles ; Z, clear spaces in the endocyst ; I, lophophore ; E ', the first, 

 E », the second, E '", the third, and E "", the fourth membrane of the en- 

 docyst ; O, bases of the outer tentacular bands ; ', fibres of the inner ten- 

 tacular bands. The third membrane, E '", is lifted from the second, E ", by 

 the action of the lower fibres of the brachial contractor, which also form the 

 knee-like ridge at L '. 



* This figure is composed from numerous drawings of diflerent individuals. 



