PLATE V.* 



Hemicidaris from the Coralline Oolite. 

 Fig. 



1 a. Hemicidaris intermedia, Fleming, p. 92. Upper surface of the test, natural size. 



b. Under surface, showing the mouth opening, with the jaws and teeth in situ. 



c. Lateral view of the test "a." 



e. Inter-ambulacral plate and tubercle, seen in profile, and magnified three diameters. 



d. Two inter-ambulacral plates, and a portion of an ambulacral area, showing the upper 



pair of semi-tubercles and poriferous zones ; magnified three diameters. 

 /. One of the jaws, magnified two diameters. 

 g. Apical disc magnified two diameters. 

 h. Test with spines attached, imbedded in a slab of Coralline Oolite. 



i. Outline of a conical variety of test in my collection. 

 j. A small spatulate tertiary spine, natural size. 

 k. The same, magnified five times. 



I. A small secondary spine, natural size. 

 m. The same, magnified five times. 

 n. A primary spine, natural size. 

 o. The same, magnified twice. 



Hemicidaris from the Portland Oolite. 



2 a. Hemicidaris Davidsoni, Wright, p. 96. Upper surface of the test, natural size. 



b. Lateral view of the same, showing the single row of semi-tubercles. 



c. Two inter-ambulacral plates, and a portion of an ambulacral area, with the poriferous 



zones ; magnified three diameters. 



d. An inter-ambulacral plate and tubercle seen in profile, and magnified twice. 



e. Mouth opening and peristome, natural size. 



* In consequence of the artist having by mistake lettered Plate IV Plate V, and Plate V Plate IV, the 

 reference in the text does not agree with the numbers now unavoidably adopted, as the text and plates were 

 both printed before the error was discovered. This, however, is the less to be regretted, as any confusion 

 which might have arisen will now be prevented when the reason for the discrepancy is explained. 



T. W. 



