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BULLETIN OE THE UNITED STATES FISH COMMISSION. 
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EXPLANATION OF PLATES. 
(Except where indicated otherwise, all drawings and photographs were made by the writer.) 
PLATE I. 
Fig. 1 . Astropecten polyacanthus , abactinal view ; enlarged to slightly over 2 diameters. 
Fig. 2. Astropecten velitaris, abactinal view; enlarged to about If diameters. 
Fig. 3. Astropecten pusillulus, abactinal view, X2. 
Fig. 4. Astropecten clenophorus, abactinal view, X2. 
Fig. 5. Same, actinal view. 
PLATE II. 
Fig. 1. Astropecten poly acanthus. Fifth inferomarginal plate and neighboring adambulacral plates. 
The upper adambulacral plate is devoid of spines, while in the lowermost (adoral) the fur- 
row spines are standing perpendicularly, X8. la. Astropecten polyacanthus. Two paxillse 
from the base of ray, X20. lb. Paxilla from ray, about halfway to tip, X20. 
Fig. 2. Astropecten velitaris. Fifth inferomarginal plate and neighboring adambulacral plates, XlO. | 
2a. Paxillse from base of ray, X20. 
Fig. 3. Astropecten ctenophorus. First 3 inferomarginal plates and neighboring adambulacral plates, 
XlO. 3a. Paxillse from near center of disk, X 20. 36. Second, third, and fourth supero- and I 
infero-marginal plates seen from the side, XlO. 3c. Tenth adambulacral plate, XlO. 3d.. 
Mouth plates; the first adambulacral shown on the right, X15. 
Fig. 4. Astropecten pusillulus. Third, fourth, and fifth inferomarginal plates and adjacent adambula- 
cral plates, a 1 , first actinal series of adambulacral spinelets; a 2 , second series; ped., pedicel- 
larian apparatus, XlO. 4a. Mouth plates, XlO. 46. Paxillse from disk near border of inter- 
radial area, X20. 
Fig. 5. Astropecten productus. Sixteenth to eighteenth superomarginal plates, and abactinal end of 
inferomarginals, showing the large lateral spines, X5; sup., superomarginal plates. 5a. 
Paxillse near base of ray, X 10. 56. Side view of a paxilla from base of ray, XlO. 5c. Adam- 
bulacral plates from near proximal end of furrow, X8; mar., inferomarginal plate. 5 d. 
Median furrow spine, X8. 5e. Mouth plates, X4. 5 f. Cross section taken at about the | 
middle of ray to show better the relation of plates, ah., abactinal integument; ad., adam- 
bulacral plate; am., ambulacral plate; inf., inferomarginal plate; sup., superomarginal plate; 
sa., superambulacral ossicle. 
PLATE III. 
Fig. 1. Ctenophoraster hawaiiensis. Adambulacral plates, actinal intermediate plates, and lower end of 
sixth inferomarginal, X8; int. pi., intermediate plate; inf., sixth inferomarginal The spines 
have been removed from the median adambulacral plate, la. Eighteenth and nineteenth 
superomarginals, from above, to show the lateral spines on upper end of the inferomarginals, 
X8. 16. Tip of an inferomarginal spine, much enlarged, lc. Diagram of an inferomarginal 
plate. The circles represent the articulation surface for spines. Id. Paxillse, about midway 
between median radial line and edge of paxillar area, from near base of ray, XlO. lc. ' 
Median spine of furrow series (adambulacral), X8. 
Fig. 2. Psilasteropsis cingulata. Madreporic body and neighboring paxillse, XlO. 2a. Adambulacral 
plates and inferomarginal plates near base of ray, X7. 26. Paxillse, edge of interradial 
area, XlO. 
Fig. 3. Psilaster attenuatas. Adambulacral and inferomarginal plates, X5. 3a. Paxillse from a large 
specimen, base of ray, XlO. 36. Paxillse from base of ray, showing usual position of spine- 
lets, XlO. 3c. Paxillse from a form with broader rays, base of ray, XlO. 3d. A single pax- 
illa, from the side; large specimen, XlO. 
