X ILLUSTRATIONS 



Fig. 3. Diagrammatic reconstruction of imagined Dipleurula 



ancestor 43 



4. Diagrammatic reconstruction of imagined primitive 



Holothurian type 44 



5. Eldonia ludwigi, new species 47 



6. Synaptula hyrdriformis (Lesseur) 54 



Figs. 7, ya. Levisia nasiita, new species 87 



8. Emeraldella hrocki, new species 204 



9. Emeraldella micrura, new species 205 



10. Sidneyia inexpectans Walcott 206 



11. Near view of Tah Peak, Robson Peak District 330 



12. Robson Peak from northwest slope of Mahto Mountain. 331 



13-16. Saukia coloradoensis, new species 376 



17. Saukia junia, new species 378 



18-20. Saukia rustica, new species 383 



