PLATE 39. 
Hyalonema (Hyalonema) obtusum gracilis LunpENreLp. 
Figures 1-10. 
1.— An intermediate acanthophore with large spines, from the basal felt; magnified 300; phot. Zeiss, 
apochr. 4, compens. oc. 6. 
2-4.— Slender-rayed acanthophore with long spines and parts of such, from the basal felt; magnified 
300; phot. Zeiss, apochr. 4, compens. oc. 6. 
5.— A very young hexactine; magnified 300; phot. Zeiss, apochr. 4, compens. oc: 6. 
6.— Part of lean acanthophore from the basal felt; magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6. 
7-10.— Pachymicrohexactines from the basal part of the sponge; magnified 300; phot. Zeiss, apochr. 
4, compens. oc. 6: 
7, a small one with stout, nearly straight rays; 
8, a large one with more slender rays; 
9, 10, a large one with very stout rays; 
9, focussed higher; 10, focussed lower. 
Hyalonema (Hyalonema) obtusum robusta LENDENFELD. 
Figures 11-41. 
11, 12.— Parts of intermediate acanthophores with large spines, from the basal felt; magnified 500; 
phot. Zeiss, H. I. apochr. 2, compens. oc. 6: 
11, a central part of a triactine; 
12, the tip of a ray. Z 
13-16.— Parts of slender-rayed acanthophores with large spines, from the basal felt; magnified 500; 
phot. Zeiss, H. I. apochr. 2, compens. oc. 6: 
13-15, tips of rays; 
16, the central part of a triactine. 
17-21.— Stout-rayed tetractine and tetractine-derivate acanthophores from the cement surrounding 
the upper parts of the large stalk-spicule imbedded in the sponge-body; magnified 100; phot. 
Zeiss, apochr. 16, compens. oc. 6: 
17, an angularly bent diactine; 
18-20, tetractines; 
21, a triactine. 
22-24.— Parts of the felt, composed chiefly of the slender-rayed acanthophores with long spines, in the 
basal part of the sponge: 
22, 23, magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6; 
24, magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 
25, 26.— Uncinate amphioxes; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 
27-29.— Parts of the uncinate amphiox represented in fig. 26; magnified 500; phot. Zeiss, H. I. apochr. 
2, compens. oc. 6: 
27, the end from which the spines diverge; 
28, the central part; 
29, the end towards which the spines are inclined. 
30.— Part of an uncinate amphiox; magnified 2000; phot. Zeiss, q. monochr. 1.7, q. oc. 10. 
31, 32— Two small, fairly regular hypodermal pentactines; magnified 50; phot. Zeiss, apochr. 16, 
compens. oc. 4: 
31, a side-view; 
32, an apical view. 
33.— View of the specimen; reduced 1: 0.85; phot. Zeiss, anastig. 480/412 mm. 
34-38.— Rhabd-acanthophores; magnified 100; phot. Zeiss, apochr. 16, compens. oc. 6. 
39.— An angularly bent diactine; magnified 100; phot. Zeiss, apochr, 16, compens. oc. 6. 
40, 41.— Larger hypodermal pentactines; magnified 50; phot. Zeiss, apochr. 16, compens. oc. 4: 
40, side-view of a fairly regular one; 
41, apical view of an irregular one with one of the lateral rays reduced. 
