PLATE CXV. 



FIGS. PAGE 



13. Arthrodesmus triangularis var. siib triangular is 



(Borge) W. & G. S. West. x 520 . 100 



4. A. triangularis var. siibtriangularis forma tri- 



quetra W. & G. S. West. x 500 . . 100 



5. A form of A. triangularis var. subtriangulnris 

 in which one semicell is biradiate and the 

 other triradiate . . .101 



6-7. A. quiriferus W. & G. S. West. x 520 . 101 



8-11. 4. crnssus W. & G. S. West. 8, x 520; 9, 10, 



and 11 a, x 500; 11 a', x 520 . . 102 



12-14. A. controversus W. & G. S. West. 12 and 14, 



x 520; 13, x 400 . . 103 



15-16. A. pliimus Turn. 15, x 500; 16, x 520 . 104 

 17. A. phimus var. Occident alis W. & G. S. West. 



x 520 . . . . 105 



18. A. quiriferus forma compacta W. & G. S. West. 



x 520 101 



