266 A. E. J^errill — Corals of the Genns Acropora. 



Figure 11. — Acropora acuminata Ver. Portion of a branch of a cotype. No. 

 1007. X 3. P. 260. 



Figure 12. — Acrojyora indurata Ver., sp. nov. Small branchlet of the type. 

 No. 6155. X 2|. P. 230. 



Figure 13. — Acrojjora urceolifera Yer., sp. nov. Tip of branch of the type- 

 No. 4187. X 2|. P. 251. 



Figure 14. — Acropora j)Tolixa Ver. Branchlet of the type. No. 1686. x2|. 

 P. 237. 



Figure 15. — Acropora microphthalma Ver. Branch of the type. No. 774. x 3. 

 P. 232. 



Figure 16. — Acropora diffusa Ver. Portion of a branch of a cotype. No. 1808. 

 X 3. P. 228. 



ADDENDA. 



Acropora effusa (Dana), see p. 229, and A. secale (Stud.), see p. 244. 



Under these species I mentioned that they are closely allied, as 

 shown by the types. 



A later comparison of the types, with reference to their relation- 

 ship, shows that, judging from these two specimens, they cannot 

 properly be united, although they agree in mode of growth and some 

 other characters. 



The corallites show very evident differences without transitional 

 forms. The axial corallites of secale are distinctly larger, through- 

 out, than in effusa, and have thicker walls. The radial corallites are 

 larger, more unequal, and more prominent; the larger ones are more 

 tubular, with thicker walls, and a more nearly terminal calicle. In 

 effusa they are more obliquely truncated with a shorter inner lip 

 and moi'e oblique calicle. 



Of course, a large series might serve to fill the gap between them, 

 but for the present they seem as distinct as most of the related 

 species. The types are both from Point Pedro, Ceylon. 



Errata. 



Page 184, line G from bottom, for Millipora read Millepora. 

 Page 222, line 19, add Pl. xxxvi. Fig. 22 ; and Pl. xxxvi B. Fig. 10. 

 Page 229, line 17, add Pl. xxxvi D. Fig. 11. 

 Page 244, line 8, omit Fig. ba and 14a. 



