60 JOHNS HOPKINS UNIVEESITY MORPHOLOGICAL MONOGRAPHS. 



su = suspensorium. 

 sub = subumbrella. 



H lateral tentacle. 

 tm median tentacle. 



v = velarium. 

 va = vacuole. 

 rl> = vitreous body. 

 vc = velar canals. 

 ve = edge of velarium. 



vfs = visual fibres, according to Schewiakoff. 

 vg = valve of gastric ostium. 

 vl = vascular lamella. 



vie = vascular lamella connecting vis with vim. 

 vim = vascular lamella of margin. 

 vis = vascular lamella of sensory niche. 

 vlst vascular lamella of sensory niche at base of stalk. 



ivc = wandering cells. 

 w-x-y-z = successive levels of Figs. 40-43 on Fig. 5. 



DESCRIPTION OF FIGURES. 



Fig. 1 . Charybdea Xaymacana, from one of the four interradial sides. 



Fig. 2. The same from above. 



Fig. 3. The same from below, the four tentacles cut off. 



Fig. 4. The same cut in halves vertically (or radially) through a perradius. 



Fig. 5. The same cut in halves vertically (or radially) through an interradius. 



Figs. 6-16. Diagrams of horizontal (or transverse) sections through C. Xayma- 

 cana at successive levels. 



Fig. 17. Tripedalia cystophora, from one of the four interradial sides. 



Fig. 18. The same from below. 



Fig. 19. The same cut in halves vertically through a perradius. 



Fig. 20. The same cut in halves vertically through interradius. 



Figs. 21-30. Diagrams of horizontal sections through T. cystophora at successive 

 levels. 



(The following are of Charybdea, except when specially stated, otherwise.) 



Fig. 31. Horizontal section through the suspensorium. 



Fig. 32. Diagram of a gastric ostium seen from the stomach side. 



Fig. 33. Diagram of a vertical section through a gastric ostium. 



Fig. 34. Diagram of a horizontal section through a gastric ostium. 



Fig. 35. Diagram to illustrate the formation of the central and peripheral gastro- 

 vascular systems of a Hydromedusa (a, b, and c) and a Cubomedusa (d). 



Fig. 36. Vertical section through the upper part of the bell, adradial, to show 

 horizontal vascular lamella. 



Fig. 37. Vertical section through the perradius, to show vascular lamella of the 

 niche of the margin. 



Fig. 38. Vertical section a little to one side of the last, to show same structure. 



Fig. 39. Horizontal section through the upper part of the sensory niche, to show 

 vascular lamella of the niche. 



Figs. 40-43 1 . Horizontal sections through the base of a pedalium at successive 

 levels, w-x-y-z, Fig. 5, to show marginal lamella. 



