790 PROCEEDINGS OF THE ACADEMY OF [DeC. , 



Fig. 8. — Hollow blastula seven hours after fertilization. Optical 



section of live egg. 

 Fig. 9. — Two-layered blastula, endoderm having arisen by delam- 



ination. 

 Fig. 10. — Young planula larva. P, posterior end, A, anterior end. 



675/1. 

 Fig. 11. — Planula larva ; posterior end enlarged ; endodermal 



cells at posterior end arranged along the axis ot the larva, 



marking line of future coelenteron, C. 



Plate XXXII, Fig. 12. — Two-tentacled polyp, in section ; four weeks 

 old. Eg. thickened basal ectoderm. 



Fig. 13. — Polyp, four months old, with five tentacles and five oral 

 lobes, lying in the same vertical planes. 



Fig. 14. — Polyp, five months old ; in typical resting attitude, ten- 

 tacles, expanded 2 mm. 



Fig. 15. — Five-tentacled polyp, showing form of cojlenteron and 

 formation of bud. 



Fig. 16. — Polyp feeding upon a worm. 



Fig. 17. — Larva twenty-three days old, exhibiting transverse 

 fission of coelenteron and elongated hydrocaulus. 



Fig. 18. — Young medusa with twelve tentacles and four sense 

 organs ; showing spherical shape and constricted bell-mar- 

 gin. 



Plate XXXIII, Fig. 19.— Thirty -two-tentacled medusa with fourteen 

 sense organs. Seventh and eighth tentacles have appeared 

 in each quadrant except quadrant A, where eighth is lack- 

 ing. Four sense organs have appeared in quadrants B and 

 D, five in quadrants A and C. 



Fig. 20. — Tentacle-tip of medusa, showing rings of nematocysts, 

 angle of tentacle, and adhesive organ on aboral side. 



Fig. 21. — Cross section of adhesive organ. O. C, gland cells com- 

 posing cement gland ; M.F., muscular flange. 500/1, 

 drawn by W. K. Brooks. 



Fig. 22. — Ectodermal pad at base of tentacle. E.P., ectodermal 

 pad ; T., tentacle ; M., mesoglcea. Radial vertical section. 

 Drawn by W. K Brooks. 



Fig. 23. — Transverse section, at bell margin, of base of tentacle, 

 showing tentacle pad, C.P. 



Plate XXXIV, Fig. 34. — Horizontal section of bell margin at level 

 of rudiment of tentacle, 1\R.; N, rudimentary nematocysts ; 

 N.R., nerve ring ; T, tentacle ; CO., circular canal. 



Fig. 25.— Radial transverse section of bell, at point of origin of 

 sense organ, S.C, showing endodermal origin; Caps., 

 sensory capsule, surrounded by ectoderm ; V., velum. 

 Drawn by W. K. Brooks. 



Fig. 26.— Tentacle tip of larva from above. 500/1. 



Fig. 27.— Nemaiocyst in detail, showing cnidocil, Gn.; ganglion 

 cell. 2000/1. 



