232 HYATT, OBSERVATIONS ON POLYZOA. 



EXPLANATION OF PLATE 15.* 

 FREDERICELLA REGINA Leidy. 



Fig. 1. View of lophophore from above with the tentacles removed, 

 showing the nerves. G, calyx; H. tentacles; I', epistome; I'', mouth; 

 M', lophophoric flexor ; U, lophophoric nerve-branches ; U' tentacular 

 nerve-branches. 



Fig. 4. Alcyonelloid variety from Tommy's Brook, Gorham, Maine. 

 The appearance of the surface of the colony is shown on the left of the 

 figure, the branches having been all removed in front in order to ex- 

 hibit the arrangement of the branches and their connection with the 

 wooden stem around which they grew. 



FREDERICELLA WALCOTTH Hyatt. 

 Fig. 2. Variety a, Georgetown, Massachusetts. 



FREDERICELLA PULCHERRIMA Hyatt. 

 Fig. 3. Sebago Lake, Maine. 



URNATELLA GRACILIS Leidy. 



Figs. 5, 6. Diagrams of figures from one of Dr. Leidy's unpub- 

 lished lithographic plates, showing the approximation of the mouth 

 and anus. I", mouth; K', stomach; K", intestine; K, anus. Fig. 6 

 is a bud and exhibits the relation of these parts in the young. 



* This plate was originally Intended to accompany the others In Vol. IV, but was un- 

 avoidably delayed; and as It Is referred to In the text as "Plate 15," that number has been 

 retained on the plate In order to avoid confusion. EDITOR. 



