PLATE 63. 
Hyalonema (Prionema) fimbriatum LENDENFELD. 
Figures 1-28. 
1-5.— Hexactine megascleres; magnified 50; phot. Zeiss, achr. aa, compens. oc. 6. 
6-9.— Hypodermal pentactines; magnified 50; phot. Zeiss, achr. aa, compens. oc. 6: 
6, apical view; 
7-9, side-views. 
10-14.— Rhabd megascleres; magnified 50; phot. Zeiss, achr. aa, RempeRs: oc. 6: 
10, 11, amphiox rhabds; 
12-14, rhabds rounded and thickened at one end. 
15-28.— Acanthophores; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 
15, a small tetractine; 
16-18, large tetractines with fairly equal rays; 
19, a large tetractine with unequal rays; 
20-24, straight or only slightly curved, more or less centrotyle: diactines; 
25, 26, slender, strongly curved, terminally thickened rhabds; 
27, 28, stout, curved, terminally thickened rhabds. 
Hyalonema (Hyalonema) placuna LENDENFELD. 
Figs. 29-34, 36-41, 51 — form B. 
Figs. 35, 42-50 —form A. 
29-34.— Mesamphidises of form B; magnified 500; phot. Zeiss, apochr. 4, compens. oc. 12. 
35.— A mesamphidise of form A; magnified 500; phot. Zeiss, H. I. apochr. 2, compens. oc. 6. 
36—41.— Micramphidises of form B; magnified 500: 
36, 39, phot. Zeiss, apochr. 4, compens. oc. 12; 
37, 38, 40, 41, phot. Zeiss, H. I. apochr. 2, compens. oc. 6. 
42-45.— Micramphidises of form A; magnified 500; phot. Zeiss, H. I. apochr. 2, compens. oc. 6. 
46, 47.— Centrotyle amphioxes of form A; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 
48-50.— Hypodermal pentactines of form A; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6: 
48, an apical view; 
49, 50, side-views. 
51.— Part of a tetractine mesamphidisc-derivate (tetradisc) of form B; magnified 500; phot. Zeiss, 
apochr. 8, compens. oc. 12. 
