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HARGITT. 



[VOL. II. 



marked a and b as to leave the bell and number of tentacles in 

 a closely trimerous symmetry. In Figs. 3-5 this evolution 

 of trimerism is so evident that it would seem to point toward 

 a preponderance of variation in this direction. As, however, 

 will be seen later, facts of a very different kind seem to point 

 as clearly in the opposite direction. It may as well be pointed 

 out in this connection that the loopings of canals shown in 

 the figures under consideration are variously simulated by 



FIG. 12. Specimen of very unsymmetrical character. 



structures shown in PI. II, Figs. 1-4, and 10. A critical 

 comparison however, while showing many unusual features 

 in these latter structures, will probably demonstrate their 

 fundamental likeness ; but this will be considered later. 



We may next consider a type of variation fairly illustrated 

 by PI. Ill, Figs. 9 and 11. As will be seen from a glance, 

 there is here exhibited a clearly defined tendency toward an 

 increase in the number of canals, hardly less marked than that 

 of decrease just considered. Indeed, specimens with bifurcated 

 canals of this character were rather more common than those 



