PLATE XV. 



Stomechini from the Great Oolite and Coral Bag. 



Fig. 



1 a. Stomechinus microcyphus, Wright, p. 213. Lateral view of the test, natural size. 

 b. Two inter-ambulacral plates, a portion of an ambulacral area, and poriferous zones, 



magnified four times. 



2 a. Stomechinus nudus, Wright, p. 21 7. Upper surface of the test, natural size. 



b. Base of the test, natural size. 



c. Lateral view of the test, natural size. 



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



zones, magnified four times. 



e. Apical disc, magnified three diameters. 



Acrosalenias from the Lias and Cornbrash. 



3 a. Acro'salenia minuta, Buckman, p. 230. Test, the natural size. Lower Lias. 



b. The upper surface of the same test, magnified four times. 



c. Base of another specimen, natural size. 



4 a. Acrosalenia iioiiciDARoiDEs, Wright, p. 234. Upper surface of the test, natural 



size. 



b. Base of the same test, natural size. 



c. Lateral view of the same, natural size. 



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



zones, magnified three times. 



e. Base of the ambulacral and inter-ambulacral areas, showing the trigeminal pores near 



the peristome, magnified three times. 

 /. Lateral view of a primary tubercle and its prominent boss, magnified three times. 

 g. Base of a small specimen, showing the mouth opening and jaws in situ. 

 h. One of the jaws of another specimen, magnified. 



i. Apical disc complete, showing the compound sur-anal plate, magnified two diameters. 

 h. Test with spines in situ, on a slab of Forest Marble. 



/. Three primary spines, showing their simple and trifid termination, natural size. 

 m. Base of a primary spine, showing the milled ring and head, magnified three times. 

 n. A secondary spine, natural size and highly magnified. 



