PLATE 24. 



Fig. 1. 101. 2. Ch^tetes lycopekdon. (Pag. 64.) 



1 a. Section of a small hemispliericul mass, showing the tubes nearly vertical to the base. 



1 4. A portion of the same magnified. 



1 c. The base of one of the hemispherical forms, where the polyps have just commenced their operations ; the 



tubes, though distinctly formed, have scarcely a i)erceptible elevation. The polyps here commenced their 



operations by attaching themselves to a valve of the Orthis testndinaria, and thence extended laterally 



on all sides. 

 1 d. A small membranous envelope of this coral, from which, in some parts, the tubes have just commenced 



rising : this substance is thin, and concentrically wrinkled on both sides. 

 1 c. A portion of an irregular massive specimen, showing a tendency to branching more distinctly than the 



specimens represented on Plate 23. 

 1/. A few tubes of the same enlarged, showing the structure before exhibited in the hemispheric masses. 

 1 g. A cylindrical branched specimen. 

 1 A. A portion enlarged, showing the radiated tubes. 

 1 i. Enlarged ends of the tubes on the surface of 1 g. 

 1 »i & 1 k. Smaller branched and cylindrical specimens. In these the direction of the tubes is more nearly in 



the direction of the axis of the coral, as shown in 1 o : they are, otherwise, similar to the previously 



noticed forms. The opening of the tubes upon the surface being likewise more oblique to the axis, they 



present a different form as represented in 1 ti. 



Fig. 2. 102. 3. Ch^etetes rugosus. (Pag. 67.) 



'i a. The specimen of the natural size. 



2 b. An enlarged portion, showing the form of the tubes and the rugose interior. 



Fig. 3. 104. 1. Receptaculites neptunii? (Pag. 68.) 



3 a. The upper surface of the specimen, showing the quadrangular or rhomboidal openings upon the outside. 

 3 4. A portion of the same enlarged, with a few of the openings, showing the aperture of the cylindrical tube 



within. The opening above is not entirely circular. 

 3 c. Vertical section of the cylindrical tubes through the centre of the mass, as they appear on a weathered 



surface. As these converge towards the base, the ends only are seen as shown in the figure. 

 3 d. Three of these tubes enlarged, showing a contraction or stricture near their upper termination, and the 



same below. 



