PLATE 4. 



Erylus oxyaster Lendenfeld. 

 Figures 1-43. 



1-23. — Megascleres; magnified 30; phot. Zeiss, planar 20 mm. : 

 1, apical view of the cladome of a dichotetraene; 

 2-5, apical views of cladomes of dichotriaenes ; 

 6, 7, pointed, straight, or slightly curved amphioxes; 



8, pointed, angularly bent amphiox; 



9, blunt, slightly curved amphiox (amphistrongyle) ; 



10, 11, styles; 



12-14, amphiox-derivates, strongly angularly bent near one end, like monaenes; 

 15, 16, amphiox-derivate with a vertically arising branch-ray, like mesomonaenes ; 

 17-19, amphiox-derivates with two or three branch-rays, like meso- or amphiclades; 



20, side view of a plagiotriaene; 



21, side view of a triaene with one simple and two bifurcate clades; 



22, 23, side views of dichotriaenes. 



24. — View of the sponge; natural size; phot. Zeiss, anastig. 480/412 mm. 



25. — Part of a superficial, paratangential section showing a pore; magnified 200; phot. Zeiss, apochr. 8, 



compens. oc. 6. 



26-34. — Microscleres and groups of such from centrifuge-spicule preparations; magnified -300; phot. 

 Zeiss, apochr. 4, compens. oc. 6.: 



a, (Figs. 26, 28-33) microrhabds; 



b, (Fig. 27) large monactine oxyaster; 



c, (Fig. 28) large diactine oxyaster; 



d, (Figs. 26, 30) large triactine oxyasters; 



e, (Figs. 30, 32-34) large oxyasters with four or more rays; 



f, (Figs. 29, 30) small oxyasters with numerous rays. 



35. — The umbilical face of an aspidaster; magnified 300; phot. Zeiss, apochr. 4, compens. oc. 6. 



36, 37. — Part of the surface of the umbilical face of an aspidaster; magnified 2000; u. v. phot. Zeiss, 



q. monochr. 1.7, q. oc. 10: 

 36, focused lower; 37, focused higher. 



38. — A ray of a large oxyaster; magnified 2000; u. v. phot. Zeiss, q. monochr. 1.7, q. oc. 10. 



39, 40. — A small oxyaster with numerous rays; magnified 2000; u. v. phot. Zeiss, q. monochr. 1.7, q. 



oc. 10: 



39, focused lower; 40, focused higher. 

 41—43. — Aspidasters; magnified 150; phot. Zeiss, apochr. 8; compens. oc. 6: 



41, rare, nearly circular aspidaster; 



42, 43, ordinary, elongate aspidasters. 



