PLATE XLVIIL 



Unless otherwise stated, the figures in this and the following plates 

 are of natural size. 



MONILOPORA ANTIQUA (page 364). 



Specimen almost completely enveloping part of a crinoidal column. 

 Partially attached specimen, with thin basal expansion and'concentrically 



wrinkled epitheca. 

 Portion of a free branch of another specimen. 

 Small piece of the last, three times the natural size, to shew the surface 



ornamentation. 



Figure 13. 



Figure 

 Figure 



14. 

 14 a. 



R^MERiA RAMOSA (page 367). 



'} terminal branch, or branchlpt, of a sp 



1, fan-shaped, terminal^branchlet of an^ 



Doir^T^onEiNUS SUBACULEATUS (page 369). 



Club-shaped terminal branch, or branchlpt, of a specimen of this species. 

 Compressed, fan-shaped, terminal^branchlet of another specimen. 



Side view of the calyx of a spr-cinien of this species. 

 Basal view of the same calyx. 



Two arm bases of the same, four times the natural size, to shew the respira- 

 tory slit (r. s. ) on one side of each. 



Genn^eocrinus Arkonensis (page 373J. 



The specimen in the Museum of the Survey referred to on page 374. 

 One of the jTimary interbrachials of this- sjtecimen, six times the natural 

 size, to shew the faint surface njarkings. 



Ancyrocrinus bulbosus (page 375). 



Specimen with the "lateral extensions" at different heights. 



Another specimen with the " lateral extensions '' at nearly the same height. 



SCALARIPORA CANADENSIS (page 378). 



The larger of the two type specimens from Thedford. 

 Outline of transverse section of the same. 



Portion of the same, four times the^natural size, to shew the apertures of 

 the zoo'cia. 



Camarotoechia Thedfordensis (page 386). 



Dorsal view of a specimen from Thedford. 



The same, three tinies the natural size. 



Front view of the same specinien, three times the natural size. 



Pleurotomaria Arkonensis (page 401). 



Apical side of the only testiferous specimen that the writer has seen. 

 Lateral view of the same. 



Orthoceras Arkonense (page 406). 



Side view of a cast of the interior of eight of the air chambers, shewing the 

 comparative closeness of the four or five septa next to the body 

 chamber and the distance apart of the posterior ones. 



Similar view of a casH} of two air chambers and part of a third. 



Outline of transverse section of the same, shewing the relative position of 

 the siph uncle. 



Figure 

 Figure 



BaCTRITES (OBLIQUESEPTATUS? Var.~ 

 15. 

 16. 



Arkonense (page 407). 



A composite figure, the posterior portion being drawn from septate speci- 

 mens, and the anterior from casts of the body chamber. 

 Enlarged view of a cast of the interior of the posterior and septate end of 

 the shell, which shews the ventral sinus distinctly on ten of the 

 septa. 

 Figure 16 tt. Outline of transverse section of the same, also enlarged, and shewing the 

 marginal and presumably ventral siphuncle. 



