PLATE II. 



UlNTACRINUS SOCIALIS. A SeRIES SHOWING VARIATIONS IN THE BaSE. 



Fig. 1. Monocyclic ; regular ; centrale of maximum size. Specimen No. X a. 



" 2. Monocyclic ; regular ; centrale of nearly minimum size. No. 60 a. 



" 3. Monocyclic ; regular ; centrale elongate. No. 89. 



" 4. Monocyclic ; irregular ; double centrale. No. X c. 



^' 5. Dicyclic ; irregular; double centrale and 1 IB. No. 248. 

 " 6. Dicyclic ; irregular ; 3 IBB. Angles of centrale radial next 



to basals, interradial next to infrabasals. No. 46 a. 



" 7. Dicyclic ; irregular ; 4 IBB. No. VI a. 



" 8. Dicyclic ; irregular ; 3 large and 2 small IBB. No. XXXVl a. 



" 9. Dicyclic ; irregular ; IBB appearing as minute points. No. 232. 



" 10. Dicyclic; regular; IBB fully developed. No. 69. 



" 11. Dicyclic; regular; IBB very acuminate. No. 39. 

 " 12. Dicyclic; regular; IBB disturbed by pressure and partly 



pushed out of level of basals. No. 47 h. 



" 13. Dicyclic ; regular ; IBB separated by pressure in fossilization. No. 36 h, 

 " 14. Monocyclic ; irregular ; quadrangular centrale and 4 basals. 



Loc. 2. No. LV z. 



" 15. Monocyclic ; irregular ; hexagonal centrale and 6 basals. No. LIV /. 



(All figures enlarged x 3. Figs. 5 and 8 by Chapman ; the others by Mrs. Eicker.) 



