PLATE VI. 



Synaptula hydriformis (Lesueur). (From Clark, 1898a.) 



Figure 1. Segmenting egg; 32-cell stage. X 225. 



2. Blastula. X 225. 



3. Pentactula larva. X 225. 



4. Ten-tentacled young. X 22. 



5. Adult animal. Natural size. 



6. Adult, opened to show inner organs. Natural size. 



7. Radial piece of calcareous ring. X 35. 



8. Interradial piece of calcareous ring. X 35. 



9. Stages of development of a piece of the calcareous ring. X 225. 



10. Anchor. X 120. 



11. Anchor-plate. X 120. 



12. Anchor-plate. X 120. 



13. Miliary granules. X 225. 



14. Calcareous rods. X 225. a. From around madrepore plate, b. From tentacles 



of a 10-tentacled larva. 



15. Vertical section through eye-spot. X 950. 



16. Horizontal section through positional organs and nerve. X 500. 

 1 ~. Vertical section through a sense-papilla and its ganglion. X 500. 



18. Vertical section through base of a tentacle, to show arrangement of parts. X 35. 



19. Tentacle. X 22. 



20. Cross-section of young tentacle, to show separation of digit-canals from tentacle- 



canal. X 225. 



21. Cross-section of body-wall. X 80. 



22. Monstrous twin larva. X 225. 



The following explanatory letters are used on this plate: 



A0=atrial opening. Mes. mesenchyme. 



BV=blood-vessel. My.=mesentery. 



CF=ciliated funnels. NR=nerve ring. 



CM=circular muscles. N=nerve. 



CK=calcareous ring. Oes. N.=cesophageal nerve. 



CT=connective tissue. 0=positional organs. 



Cart. R.=cartilaginous ring PT=primary tentacle. 



Cir. C.=circular canal. PV=polian vessels. 



Ect.=ectoderm. RN radial nerve. 



Epid. epidermis. SC=stone canal. 



Epith.=epithelium. S0=secondary outgrowth of hydrocoel. 



GG genital gland. TC canal of tentacle. 



ga.=ganglion. TN=teutacle nerve. 



LM longitudinal muscles. TV=tentacle blood-vessel. 



LGO=larval glandular organ. V valve. 



M=mouth. WP=water pore. 



