THE BRITISH SECONDARY EOCKS. 55 



each side. The largest specimens (5-5 millims.) are the flattest, having 

 the widest cirrhus-free space. In the smaller ones the dorsal surface 

 is more generally convex, and the plate has less distinct sides. 



Yentral surface flat, with a round axial opening. Basal grooves 

 shallow, slightly widening from central to distal ends. 



Locality. The Great Oolite, Bath. 



There are five specimens in the British Museum, one of which ia 

 very small, and the others more nearly equal. All are very much 

 worn. 



BemarTcs. This, the earliest known Comatula, is a good typical 

 Actino7netra, so far as can be judged from the appearance of the cen- 

 trodorsal, which is very similar to that of many recent species from 

 the Philippines and Malay Archipelago. I dedicate it to Johannes 

 Mtiller, to whom we are indebted for its generic name. 



EXPLANATION OF PLATE V. 



Fig. 1. Antedon paradoxa, from the Upper Chalk, Dover. Ventral surface of 

 centrodorsal. X 3. 



2. Antedon rugosa, n. sp., from the Chalk. Centrodorsal : a, ventral sur- 



face ; h, dorsal surface ; c, from the side. X 2. 



3. Ventral surface of the centrodorsal of a new (recent) Antedon from 



Heard Island. The lower ends of the ribs on the walls of the inter- 

 nal cavity are visible through the axial opening. X 3. 



4. Antedon cBquiraargi7tata, n, sp., from the Gault, Folkestone. Centro- 



dorsal and radial pentagon : a, from above ; b, from the side, radial 

 view ; c, from the side, interradial view, showing the end of one of 

 the basal rays between the lower angles of two contiguous radials. 

 X4. 



5. Antedon rotunda, n. sp., from the Haldon Greensand. Centrodorsal : 



a, ventral surface ; h, from the side ; c, dorsal surface. 



6. Actinometra MilUeri, n. sp., from the G-reat Oolite, Bath. Centrodorsal: 



a, ventral surface ; b, from the side ; c, dorsal surface. X 3. 



7. Antedon prisca, n, sp., from the Bradford Clay, Cirencester. Side view 



of two contiguous radials, showing the end of a basal piece between 

 their lower angles. X 6. 



8. Actinometra abnormis, n. sp., from the Bradford Clay, Cirencester. 



Centrodorsal : a, ventral surface ; b, from the side , c, dorsal surface. 

 X8. 



