PLATE 51 



Fig. 1. Ctenacanthus nodocostatus, n. sp. Type. Complete spine. Onginal is 

 an impression in sandstone, and the figure is from a wax squeeze of it. Natural 

 .size. E 2083, p. 159. 



Fig. 2. Acanthodes concinnns Whiteaves. Enlargement of shagreen, X about 

 15. Taken from specimen E 2485 (see te.xt-fig. 50), p. 141. 



Fig. 3. Acanthodin spine, in matrix. X 6. E 2486, p. 142. 



Fig. 4. Acanthodes concinmis Whiteaves. Pectoral fin-spine of specimen of 

 which sha<j;reen is figured (this plate, fig. 2). E 2485. X 35, p. 141. 



300 



