Plate VIII. 



Figp. 1-12. HyaJascHS scu/amiensis Ij. P. 88. 



Fig. 1. tSpiciiles on and near the dermal «iirface in obli(|U(^ view ; Sonie 

 dernialia, hypodennalia and parenchymalia. .50 x . 



Fig. 2. Gastral layer (below) and some .spicules (|)arenchymalia and 

 oxyliexasters) directly beneath it ; from a section. .3(J x . 



Figs. 3 — 16. Hijalasciis (jiganteus Ij. P. 100. 



Fig. .J. A small portion of the dermal surface, much abraded, of the 

 type specimen [)reserved in ihe British Museum. Nat. size. 



Fig. 4. A small portion of the gastral surface of same. Nat. size. 



Fig. ."). Spicules on and near the dermal surface in oblique view : some 

 dermalia, a hypodermal ]ientactin and some parenchymalia, .30 x . 



Fig. 6. Gastralia and hy[)()gastral beams in surface view. .00 x . 



Fig. 7. Gastral hexactin. 300 x. 



Fig. 8, 9. Dermalia. 300 x. 



Fig. 10. Disojhexaster. 300 x. 



Fig. 11. Portion of the same, more highly magnified. 



Figs. 1'2-16. Various forms of ox3diexaster. 300 x. 



Figs. 17-2.5. Staurocalyptas 'hticrochclus Ij. P. 202. 



Fig. 17. The ty[)e specimen (S. C. M. No. 4.50). Nat. size. 



Fig. 18. Dermalia. 300 x . 



Fig. 19. Gastralia. 300 x. 



Fig. 20. Oxyhexaster from a deep ])art of tlie wall. 300 x . 



Fig. 21. Oxyhexaster from periphery of the wall. 300 x . 



Fig. 22. Microdiscohexaster. 300 x . 



Fig. 23. Discoctaster. 300 x . 



Fig. 24. Dermal layer in obli(|U(' view ;uid underlying spicuU;s, some 



hypodermal [)entactins protruded as prostalia. .50 x , 

 Fig. 2.5. Gastral layer in surface view ; some discoctasters and ox\liexasters 



in situ. .50 x . 



Figs. 2f)-28. AalosatvuH nclmhxi Ij. 1\ 110. 



Fig. 2(!. Dermal layer and liy[)odermal Ix'ams (ectosomal skeleton) in 



surface view. ,50 x . 

 Fig. 27. Two gastralia (below) and adjoining spicules in situ. Amongst 



the latter, a macrodiscohexaster. .30 x . 

 Fig. 28. Central spliere of macrodiscohexaster, examined in glycerine, 



showing the axial cross. 440 x . 



