14 G. HERBERT FOWLER. 



4. Fowler.— "Quart. Journ. Micr. Sci.," Oct., 1885; and 



" Studies from the Biological Laboratories of the 

 Owens College," Vol. i., 1886. 



5. Wilson.—" Mitth. Zool. Sta. Neap.," Bd. v. 



6. Von Heider.— " Sitz. k. Akad. Wissench.," 1879. 



7. Dana. — " Zoophytes of the Wilkes Expedition." 



8. Von Koch.—" Morph. Jahrb.," Bd. vi. 



DESCRIPTION OF PLATE I. 



a. Polyp cavities, cut obliquely, a'. Polyp cavities, cut trans- 

 versely. Ab. Abaxial (ventral) septum. Ax. Axial (dorsal) septum. 

 C. Costa?, ex. Central cavity, continuous with the apical polyp. 

 c 1 . External longitudinal canals between the costse. c 2 . Internal 

 longitudinal canals, c 3 . Kadial and transverse connecting canals. 

 Co, Corallum of the main branch, d. Cut edges of the endoderm 

 and mesoderm lining the coelenteron. ed. Ectoderm, en. Endoderm. 

 ext. b. w. External body wall of ectoderm, mesoderm, and endoderm. 

 M. Mesentery, showing the endodermal swelling, me. Mesoderm 

 lamella, S. Septum. S. C. Septal Columella-plate. St. Stomato- 

 dasum. Th. Theca of polyp. Z. Zooxanthellse. x. Fusion of costse 

 over ext. long, canals. All except Fig. 10 are from Madrepora 

 Durvillei. 



Fig. 1. Dorsal view of the corallum of two fragments of a branch, 

 bearing calicles, and branchlets formed of other calicles. 



Fig. 2. Ventral view of the same specimens ; one of which is entirely 

 bare of calicles on this side, and on the other only a few 

 are present. 



Fig. 3. Transverse section of a branch, showing the polyp cavities, 

 the central cavity, and the canals running in various direc- 

 tions. The concentric arrangement of the latter is well 

 shown. Into the central cavity project the six septa. In 

 two of the innermost ring of polyps, the axial and abaxial 

 septa have fused into the septal columella-plate. 



