PLATE VII. 



PAGE . 



Fig, 1. Ptilodictya PLUMARIA, James. — A specimen showing the general 



characters of this species; natural size, 



la. Tangential section showing, on the right, the longitudinal, and, on the 

 left, the oblique series of cells ; magnified 18 diameters. 

 Fig. 2. Ptilodictya nodosa, James. — View of the type specimen of this 



species, . . - . . . . — 



2a. Surface of same, enlarged 18 diameters. 

 Fig. 3. Ptilodictya pavoxia, D'Orb. — The basal portion of a frond of this 



species, 163 



3a. Represents a specimen expanded rapidly from the sub-solid articu- 

 lating process; natural size. 

 3b. Tangential section, magnified to 18 diameters. 

 3c. Longitudinal section, equally enlarged. 



3o\ Represents the non-poriferous margin, and a few adjoining cells; 

 magnified to 18 diameters. 

 Fig. 4. Ptilodictya maculata, n. sp. — A small example of this species, . 163 

 4a. Tangential section, enlarged to 18 diameters, showing numerous 

 pseudo-septa. [This is a variable character, and is more or less 

 developed in nearly all species of Ptilodictya.] 

 Fig. 5. Ptilodictya ramosa, n. sp. — This figure represents a very fine speci- 



men of this species; natural size, . 164 



5a. Surface of same enlarged to 18 diameters, showing the characters of 



the surface from the central portion of a branch to the sharp edge. 

 Fig. 6. Ptilodictya briareus, n. sp. — The most complete specimen seen of 



this species, 165 



6a. Surface of same enlarged to 18 diameters. 



66. Tangential section taken just above the wedge-shaped, articulating 

 process; magnified to 18 diameters. 



Fig. 7. Ptilodictya hilli, James.— A specimen showing the articulating 

 process and the transverse ridges, which are characteristic of this 



species; natural size, 



7a. A tangential section, showing that the cells in the transverse ridges 

 have thinner walls than those in the grooves ; enlarged to 18 

 diameters. 



Fig. 8. Graptodictya nitida, n. sp. — A specimen of this species; natural 



size, • 166 



8a. Surface of same, enlarged to 18 diameters. 

 Fig. 9. Dicranopora internodia, Miller and Dyer. — Represents a specimen 

 of this species that preserves five segments in connection; natu- 

 ral size, 166 



9a. The lower portion of a segment, enlarged to 18 diameters. 

 Fig. 10. Arthropora shafferi, Meek's sp. — Portion of a more complete 

 specimen, giving a tolerably good idea of the growth of the 



zoarium, 167 



10a. Surface of this species enlarged to 18 diameters; many of the cells 

 are closed by opercula. 



