396 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



Plate 49. Demuisterias imbricata. 



Fig. 1. Specimen from Barclay Sound, British Columbia. 



2. Left figure: portion of arm of epecimen from Puget Sound; the integument has been stripped 

 from right half, showing plates; on left half, numerous pedicellariie, in the abactinal 

 integument. 

 Right figure: portion of abactinal wall of ray, dried and viewed from coelomic side showing 

 plates. 



Plate 50. 



Fig. 1. Leptychaster pacificus; two adarabulacral plates, proximal third of ray, X 10. la. Same; abac- 

 tinal plates, papular area, at base of ray, from inside, X 20. 



2. Leplychaster anomalus; two adambulacral plates from about middle of ray, X 10. la. Same; 



abactimal plates at base of ray from inside, X 20; from station 3263. 



3. Psilaster pectinaius; fifth, sixtli, and seventh adambulacral plates, medium-sized individual, 



station 3307; spines have been removed from middle plate, X 10. 3a. Same; adme- 

 dian paxillse, base of ray, X 10. 36 and 3c. Same; two views of odontophore, X 10. 



4. Astropecten armatus; abactinal plates near base of ray, from inside, X 10. The large plates to 



left (r) constitute the carinal or radial series of ray. 



5. Astropecten californicus; abactinal plates, from inside, X 10; r, radial series. 



Plate 51. 



Fig. 1. Astropecten omatissimus; sixth, seventh, and eighth adambulacral plates, type, X 12. la. 

 Same; abactinal plates near base of ray from within, X 20; r, radial series; ad, adradial 

 series; p, papula. 16. Same; section of arm, X 6, showing the marginal, adambulacral 

 (ad), superambulacral (so), and ambulacral (amb) plates with their dorsal serrate edges. 

 Ic. Same; a large paxilla from base of ray of type, enlarged. 



2. Astropecten californicus; adambulacral plates, near base of ray, X 10; specimen from station 



4559 having more pointed superadambulacral spines; ab, aboral enlarged subambulacral 

 spine. 2a. Same; adambulacral plate from near base of ray, type, X 10. 



3. Astropecten arviatus; ninth and tenth adambulacral plates, X 10; specimen from Beacon 3 



Shoal, San Diego, California. 



Plate 52. 



Fig. 1. Dipsacaster eximius; ninth and tenth adambulacral plates, X 6; ad, adoral side of plate, la. 

 Same; paxilla from radial area at base of ray, X 10. 16. Same; larger paxilla from near 

 center of disk, X 10. \c. Same; abactinal plates from within, X 10; r-r, median radial 

 series. Note the more numerous papulae about the radial plates. 



2. Dipsacaster borealis; eighth adambulacral plate, X 6. 2a. Same; one of the largest paxilla; 



(except those on madreporic plate) from baee of ray, X 10. 26. Same; abactinal plates, 

 base of ray, X 10; r-r, median radial series, a; -x, course of adradial muscle band . 



3. Dipsacaster Ixtmophilui; ninth adambulacral plate, X 6. 3a. Same; one of the furrow spines, 



X 6. 36. Same; paxilla from radial region, base of ray, X 10. 



4. Dipsacaster anoplus; fifth and sixth adambulacral plat&s, X 10. 4a. Same; large paxilla 



from base of ray, X 10. 



Plate 53. 



Fig. 1. Thrissacanthias penicillatus; abactinal paxillie from near base of ray, type, X 10. la. Same; 

 side view of a larger paxilla from disk, X 10. 16. Same; eighth adambulacral plate, 

 type; X 6; the adoral side of plate is on the right. Ic. Same; eighteenth plate from 

 medium-sized specimen, X 6; ad, adoral side. Id. Same; bifid marginal spines, type, 

 X 6; Buperomarginal to left, inferomarginal (2) to right. Ic. Same; abactinal plates at 

 base of ray, X 5; r-r, radial series. 

 2. Dipsacaster Ixtmophilus; abactinal plates, baee of ray, X 10; r-r, radial series. 



