PLATE 5. 
Fig. 1. 401. 6. Buthotrephis gracilis. (Pag- 18.) 
1 a. A small delicate specimen of this species. The engraving represents the branches rather too slender and 
acute. 
1 b. An elongated stipe with numerous branches. 
It. A fragment with several branches which are again subdivided. 
1 d. A large individual having fewer branches.in proportion to its size, than the preceding, and approximating 
in character to the succeeding forms. 
Fig. 2. 402. 7. Buthotrephis gracilis, var . intermedia. (Pag- 19.) 
2 a. A slender specimen with few branches. 2 6. A more rigid specimen with numerous branches. 
Fig. 3. 403. 8. Buthotrephis gracilis, mr. crassa. (Pag- 19.) 
3 a, b, c, are common forms of this species in its proper and coarser varieties: 
3 d. A large specimen, with the branches extremely diverging and mostly simple. 
