PLATE XVII. 



Acrosalenias from the Lias, Cornhrash, and Coral Bag. 



Fig. 



1 a. x\cROSALENiA UECORATA, Haime, p. 247. Upper surface of the test, natural size. 

 h. Under surface of the test, natural size, showing the concave base and equal-lobed 

 peristome. 



c. Lateral view of the same, natural size, showing the magnitude of the equatorial 



tubercles. 



d. Upper surface of the inter-ambulacral and ambulacral areas, magnified four times. 



e. Two equatorial inter-ambulacral plates and a portion of the ambulacral area, magni- 



fied four diameters. 

 / The apical disc, with all the elements of the sur-anal plate in situ, magnified three 



times. 

 g. The apical disc of another specimen, showing the single crescentic genital plate, 



magnified four times. 

 li. Base of the ambulacral and inter-ambulacral areas, with two lobes of the peristome, 



magnified four times. 

 /. Lateral view of an equatorial primary tubercle, with its highly crenulated boss. 

 k. Slab from the Coralline Oolite of Malton, with tests and spines in situ, natural size. 

 /. Primary spine, natural size, with base and transverse section, magnified four times. 

 m. Secondary spine, magnified, showing the longitudinal lines on its surface. 



2 a. AcROSALENiA MiNUTA, BucJcman, p. 230. Test, the natural size. 



b. Base of the same, magnified three diameters. 



c. Upper surface of the same, magnified three diameters. 



d. Lateral view of the same, magnified three diameters. 



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



magnified ten times. 



3 a. AcROSALENiA spiNOSA, Agassiz, p. 238. Upper surface of the test, natural size. 



b. Base of the same, natural size. 



c. Lateral view of the same, natural size. 



d. Two inter-ambulacral plates, a portion of the ambulacral area, and poriferous zones, 



magnified four times. 



e. The conical boss, with its crenulated summit, and perforated tubercle, magnified. 

 /. The apical disc, with its single sur-anal plate, magnified four diameters. 



