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THE PRESIDENT'S ADDRESS. 81 



Description of Plate 7. 



Fig. 1. Ideal primitive tetraxon. 



2. Plagiotriaene of Ecionema carteri, x 52. 



3. Orthotriaene of Pilochrota homelli, X 52. 



4. Anatriaene of Tetilla poculifera, X 52. 

 4a. Cladome of 4 x 230. 



5. Protriaene of Tetilla pocidifera, x 52. 

 5a. Cladome of 5 x 230. 



6. Dichotriaene of Ecionema laviniensis, x 52. 

 6a. Cladome of 6, seen from above, x 52. 

 ,, la-Id. Ends of triaenes of Stelletta vestigium, with reduced 



cladi, x 230. 

 ,, 8. End of oxeote of Stelletta vestigium, x 230. 

 ,, 9. Angulated oxeote of Pachychalina subcylindrica, x 360. 

 10. Straight oxeote of Reniera pigmentifera, x 360. 

 ,, 11. Style of Axinella halichondrioides, x 230. 

 12. Tylostyle of Hymedesmia curvistellifera, X 230. 

 13. Spined tylostyle of Myxilla tenuissima, x 530. 

 ,, 14a-14A. Astrose microscleres of Xenospongia patelliformis, 



X 530. 

 15. Microxeote microsclere of Desmacella tubidata, x 230. 

 16. Toxiform microsclere of Gellius angulatus var. canalicu- 



lata, x 230. 

 17a, lib. Sigmata of Gellius angulatus var. canalicidata, x 230. 



(Note the angulation of the spicule, suggesting 



derivation from a diactinal microxeote, such as is 



represented in figs. 26a-26c.) 

 18a, 186. Toxa of Toxochalina robusta var. ridleyi, X 230. 



19. Sigma of Desmacidon reptans, X 512. 



20. End of sigma of Paresperella serratohamata, x 530. 



21. Diancistron of Vomerula or Hamacantha, x about 200. 



22. Isochela of Esperiopsis pulchella, front view, x 284. 

 ,, 22a. Side view of same, x 284. 



23. Anisochela of Cladorhiza jientacrinus, front view, x 700. 

 ,, 23a. Side view of same, x 700. 

 24. Anisochela of Cladorhiza (?) tridentata, front view, 



x 360. 

 24a. Side view of same, x 360. 

 Journ. Q. M. C, Series II. No 72 6 



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