256 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



a. Dull dark olivo brovm above, with dark reddish spots at center of disk ; below 

 orange around ede;e, rest lisiht yellow. 



I. Dark reddish brown shading to dark grayish green along radii and center 

 of disk (similar to 1/, but browner). 



c. Above, pale dull grayish green; the primarj^ plates are greenish white or 

 gray, the papular areas dull grayish green; sparsely spotted Math very dark green; 

 papulje when extended give the surface a brownish cast, leaving the plates in 

 sharp relief. Below, pale straw yellow, darker at edge of disk. 

 • 4. Miscellaneous. 



a. Above, pale greenish, deep cadmium, and orange, min gled with large 

 irregidar spots of very dark olive green on radii and center of disk. 



6. Same, but green spotting all over. Even other combinations may be found 

 at Monterey Bay. 



Anatomical notes. — Externally the abactinal plates have a crescent form rounded 

 at either end, and the surface is marked by a sUght elevation, also of crescent form, 

 wluch bears the granules. The papular areas, outside the central region of disk, 

 have a convex margin toward edge of ray (corresponding to the concavity of the 

 plate) and the opposite side is sometimes concave. These areas are everywhere 

 broken up by small intermediate ossicles, which encroach onto the border of the 

 primary plates, and form an incomplete irregular network on the areas. Between 

 the secondary ossicles emerge the papulae. Sometimes two or more of these granuh- 

 form ossicles coalesce to form an irregular rod. In the center of the disk the papular 

 areas are much larger than elsewhere, containing more papulis and more secondaiy 

 plates, and the primary plates are smaller, except in the case of the "primary 

 apicals," some of which form a pentagonal ring surrounding the apical area. The 

 photograph will show the arrangement and form of the plates, which have been 

 treated with caustic potash and the spines removed. 



Viewed from withm, the dorso-lateral plates have four lobes by which they 

 imbricate, the carinals are transversely elongated and nearly obloiig, and the adra- 

 dials are elongated transversely but are triangular. (See pi. 56, fig. Sa.) 



The actinal intermediate plates are very numerous, imbricated, and marked by a 

 slight spiniferous elevation. The inner edge of this elevation or convexity (except 

 on the small peripheral plates) is marked by two to four shght serrations, trans- 

 verse to the long axis of plate. The serrations are fairly large, but in very low 

 bas-relief (fig. 8, pi. 56), and can bo seen only when the plates are thoroughly 

 cleaned. The spinelets are inserted just back of the serrations. The surface of the 

 adambulacral plates has three similar markings, of which the median is largest. 



Variations. — Rays usually five, but occasionally six, and rarely seven; one 

 seven-rayed specimen (Monterey Bay) has three madreporic bodies. Sometimes 

 the tip of a ray is bifurcate, each branch having a normal furrow and plating. Tliis 

 species is stellate, but the length of the major radius varies from 1.7 to 2 r; it ia 

 apparently never pentagonal, as is commonly the case with A. pectinifera (or a 

 variety). The amount of Mebbing on the actinal spines is variable, as is the apparent 

 thickness of the epidermis (variability perhaps due to fixation). Some combs are 

 free nearly to base, others webbed nearly (but not quite) to tips; all have more or 



