PLATE III. 



Tropidaster pectinatus, Forbes. 



From the Middle Lias. 



Tig. 



1. Tropidaster pectinatus, Forb., p. 102. Showing the ventral surface, and a lateral 



view of the curved rays in small specimens. 



2. Dorsal surface of two individuals on one slab, natural size. 



a. Dorsal surface of a ray magnified, to show the arrangement of the middle ridge with 



its imbricated plates, and the tubercles on the inter-ambulacral portions. 



b. Ventral surface of a ray, and part of the disc, showing the ambulacra and the angle- 



plates. 



c. Ambulacral plates, and spiniferous plates bordering the ambulacral avenue, magnified. 



d. Marginal plates, magnified. 



/ Madreporiform body, magnified. 



3. A large specimen with smaller attached, both natural size. 



