PLATE 18. 
Staurocalyptus hamatus LenpENFELD. 
Figures 1-14. 
1—4.— Two small discohexasters; magnified 2000; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10: 
1, 2, one small discohexaster ; 
1, focussed higher; 2, focussed lower; 
3, 4, another small discohexaster; 
3, focussed higher; 4, focussed lower. 
5, 6.— Views of the sponge after removal of the Dicranodromia; reduced 1: 9.85; phot. Zeiss, anastig. 
480/412 mm.: 
5, from below; 
6, from above. 
7.— A small discohexaster; magnified 600; phot. Zeiss, H. I. apochr. 2, compens. oc. 6. 
8-10.— Side-views of hypodermal pentactines; magnified 30; phot. Zeiss, planar 20 mm. 
11, 12.— Part of a spicule-group; magnified 600; phot. Zeiss, H. I. apochr. 2, compens. oc. 6:° 
11, focussed higher; 12, focussed lower; 
a, dermal rhabd; b, small discohexasters. 
13.— Part of a large rhabd of abnormal structure; magnified 600; u.v. phot. Zeiss, q. monochr. 6, q.oc. 10. 
14.— The sponge with the Dicranodromia seen from the front; natural size; phot. Zeiss, anastig. 
480/412 mm. 
Holascus edwardsii LENDENFELD. 
Figures 15-26. 
15.— Group of slender-rayed comital triactines; magnified 30; phot. Zeiss, planar 20 mm. 
16.— Group of slender-rayed comital triactines, tetractines, and pentactines; magnified 50; phot. 
Zeiss, apochr. 16, compens. oc. 4. 
17, 18.— Hypogastral hexactines; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 4. 
19-21.— Hypodermal hexactines; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 4. 
22.— Surface-view of the skeleton of the body-wall. The soft parts and most of the smaller spicules are 
removed. The large choanosomal pentactines are still nearly in their natural position. Magni- 
fied 7.5, phot. Zeiss, planar 50 mm.: 
a, large choanosomal pentactines; b, comitals. : 
23.— The central part of a slender-rayed, comital spicule with two fully developed long rays, one con- 
siderably reduced ray, and two insignificant ray-rudiments which appear as slight protuberances; 
magnified 600; phot. Zeiss, apochr. 4, compens. oc. 12. 
24-26.— The distal part of the distal ray of three hypodermal hexactines; magnified 600; phot. Zeiss, 
apochr. 4, compens. oc. 12. 
