PLATE CIX. 

 FIG. i. Orthasterias tanneri Verrill. Cotype. Actinal side of disk, to 



show jaws and peroral spines; X 



FIG. ia. The same specimen. Dorsal side of disk, showing spines and 



pedicellariae ; X 2. 



FIG. ib. The same specimen. Section of a ray, showing inner surface 



of skeleton; cut through ambulacral plates and flattened 

 out ; a, a, ambulacral plates ; ad, ad, adambulacral plates ; 

 b, b, peractinal plates; m, m, inferomarginals ; m' ', m', 

 superomarginals ; d, d, dorso-lateral plates and transverse 

 connective ossicles; s, s, adambulacral spines; c, c, median 

 radial or carinal plates ; X 2%. 



FIG. 2. O. columbiana Verrill. Type. Transverse section of a ray ; 



a, a, ambulacral plates; ad, ad, adambulacrals ; b, b, per- 

 actinals; m, m, inferomarginals; m', m', superomarginals; 

 d, d, dorso-lateral plates and transverse ossicles ; c, carinals ; 



X2. 



FIGS. 20, 2b. The same specimen. Two parts of a transverse section of a 

 ray, split through the ambulacral plates and flattened out, 

 to show inner surface. Lettering as in fig. ib, except that 

 d, d; d' d'; d", d" show the three rows of dorso-lateral 

 plates ; X 2. 



FIG. 3. Patiria miniata (Brandt). Central part of disk and madreporic 



plate, with spinules removed ; X 2. 



FIG. 4. Enoplopatiria siderea Verrill. Type. Dorsal view of middle 



of a ray with spinules removed ; X 2. 



(220) 



