DESCRIPTION OF 23 



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Fig. 1. ZAPHRENTIS SPINULIFERA. 650 



1 a. Lateral view of a specimen of medium size. 



1 



I b. View of the calyx showing the rays. 



Fig. 2. ARCHIMEDES REVERSA. 652 



2. The axis preserving the bases of the frond, showing gradual expansion 



towards the middle and diminution above. 



Figs. 3, 4 & 5. ARCHIMEDES WORTHENI. 651 



3. A portion of the axis of a specimen of this species, showing the usual 



characteristics, together with several of the small props or braces ex- 

 tending from one volution to the other. 



4 a. A fragment of the axis preserving several volutions of the frond, as 

 seen from the inner side. 



4 ft. A portion of the inner celluliferous surface enlarged, showing arrange- 



ment of cellules. 



5 a. Exterior of the same specimen, showing the fenestrules. 



5 b. Enlargement of surface of fig. 5 a, showing form of fenestrule. 



Figs. 6 & 7. PTYLOPORA PROTJTI. 653 



6 a. Celluliferous side of a specimen, natural size. 

 6 ft. The same enlarged. 



6 c. A portion still farther enlarged. 

 7. Exterior of the same species. 



Figs. 8, 9 & 10. PENTREMITES CONOIDEUS. 655 



8. A full-grown individual, which is more elongated than usual. 



9. A specimen of ordinary form and size. 



10. The base, showing form of basal plates and bases of the pseubambu- 

 lacral areas. 



Fig. 11. PENTREMITES KONINCKANA. 656 



II a. A specimen, natural size. 

 11 ft. The same enlarged. 



11 c. Summit of the same enlarged. 



Fig. 12. DICHOCRINUS SIMPLEX. 654 



12 a. Basal view of specimen. 



12 ft. Lateral view of the same. 



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 12 c. view of the summit. 



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