ClarTc — Six Neto Starfishes from the Gulf of California. 55 



and arm bases commonly have from three to six very small spines of 

 different sizes about the bases of the larger. 



The papul?e are large, abundant, and conspicuous, occurring all over 

 the abactinal surface to within 20 mm. of the tips of the arms; they are 

 slightly smaller in the mid-radial line of the arms and in the center of the 

 disk than elsewhere. 



The madreporite is oval, measuring 4 mm. by 3 mm., the longer 

 diameter radial; the surface is elevated, high, evenly convex, covered 

 with numerous fine irregular ridges ; its center is one-third of the distance 

 between the odd interradial superomarginal and the center of the disk. 



The odd interradial superomarginal is six sided ; the abactinal and the 

 two adjacent sides are of about the same length ; the former is slightly 

 concave, and the two latter are produced into a slight spine at the lower 

 angles ; the proximal border, adjoining the odd interradial inferomarginal, 

 is about as long as the opposite side, straight, or slightly convex; the two 

 lower lateral sides are about twice as long as the others, slightly concave. 

 The abactinal surface of the plate within the outer face is produced into 

 a rounded tubercle, not especially conspicuous, which bears on its outer 

 side (not on its summit) a rough spine only slightly larger than the large 

 spines of the disk, directed outward and more or less downward. 



The superomarginals are low and long, mostly about twice as long as 

 broad; the first is iri*egularly polygonal or quadrate, about as long as 

 broad ; the following are irregularly rhombic with the distal and proximal 

 angles truncated; the suture between the adjacent superomarginals slants 

 strongly inward, the abactinal end being more distal than the actinal. 

 Each superomarginal bears in its upper two-thirds, springing from a 

 common elevation, two slender spines, one directly above the other; the 

 uppermost is the longer, resembling the long spines of the center of the 

 disk but somewhat more slender ; the lower is shorter and more slender ; 

 in the outer half of the arms the latter disappears. The common elevated 

 base bearing these spines carries a few spinules. 



The odd inferomarginal is elongated dorso-ventrally ; the actinal third 

 lies on the actinal surface, while the abactinal two-thirds stands almost 

 vertically, forming with the corresponding superomarginal the side wall 

 of the interbrachial arc. Viewed laterally the odd interradial infero- 

 marginal appears six-sided ; the actinal side, forming the border between 

 the actinal and abactinal surfaces, is about twice as long as the other 

 sides, which are all of equal length ; that part of the plate which lies on 

 the actinal surface is approximately semicircular, with two slight tubercles 

 midway between the midradial point and the point of union with the 

 adjacent inferomarginals. The plate bears a vertical median column of 

 three slender spines of which the uppermost, situated in the center of the 

 lateral surface, is 3 mm. long; the next, situated on the lateral surface 

 just at the actinolateral border, is of about the same size; the third, situ- 

 ated just beyond the center of the actinal surface, is much smaller. 



At first the inferomarginals are slightly displaced distally, but after 

 the proximal fourth of the arm they correspond to the superomarginals; 

 in the proximal fourth of the arm they resemble the superomarginals in 



