PLATE 11. 

 Pectinatella magnifica Leidy. 



Fig. l.# Enlarged longitudinal section exhibiting a portion of the left 

 arm and the left side of the tcdy, of a p olypide. The ganglion, however, is 

 from the right side of the body, towards the observer, and is supposed to be 

 pressed inwards, and away from the observer, in order to show its relation to 

 the neural partition and the polypidal nerve. (Norway, Me.) H, tentacles ; 

 H', tubular interior of the tentacles ; G, calyx; H", cilia; O, bases of the out- 

 er tentacular bands ; ', fibres of the inner tentacular bands, seen from the 

 outside; I', epistome ; P, one-half of the median muscle of the epistome ; 

 P ', left lateral muscle of the epistome; E, parietal fibres, probably abnor- 

 mal, enveloped by the fourth membrane; I, lophoj hore ; I", mouth; E' 

 the first, E", the second, E'", the third, and E"", the fourth membrane 

 of the endocyst; F, brachial collar ; F' neural partition; K, oesophagus ; 

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

 valve; K, anus; J', the first, J", the second, J'", the third, and J"", the 

 fourth membrane of the alimentary canal;. S ', right ganglion; T, right 

 lophophoric nerve trunk severed near the base ; T ', right epistomical nerve 

 trunk ; T ", right brachial nerve trunk severed near the base ; T '", right, 

 polypidal nerve trunk. 



Fig. 2. Enlarged ganglion of another specimen from the same colony 

 as fig. 1, showing the extreme variability of the ganglia and nerve trunks. 

 T, right lophophoric nerve trunk; T', right epistomical nerve trunk; 

 T", right brachial nerve trunk; T'", right polypidal nerve trunk. 



Fig. 3. Shows the same ganglion contracted, the nerve trunks indica- 

 ted by the same letters. 



* This figure is composed from numerous drawings of different individuals. The 

 number of the membranes in the tentacles, as has been explained in the text, was 

 inferred but not observed. 



