94 NATURAL HISTORY BULLETIN 



The dorsal surface of the rays is covered with a broad, very- 

 irregular band of large, swollen, evenly convex, unequal, round- 

 ish plates, mostly in contact radially to a variable extent. These, 

 where most regular, seem referable to three rows, by reason of 

 the large, irregular papular areas between them. The plates that 

 seem to belong to the median row average larger and more prom- 

 inent than the others, but are unequal and seem to be crowded 

 out of position by the growth of others. 



Outside of those described, and on the sides of the ray, there 

 is a much more regular row of dorsolateral plates, which are 

 also roundish and strongly convex, but less so than those above. 

 They are in serial contact, but are joined to the row above by 

 small connective ossicles and large intervening papular areas, 

 which form here a regular row. The papulae are small and very 

 numerous in these and the dorsal groups. Twenty to thirty or 

 more can be counted. 



All these plates, as well as those below, are covered closely 

 with small, nearly uniform rounded granules, which also sur- 

 round the papular pores, but there become angular, so that four 

 or five around each pore look like small valves. 



The two rows of marginal plates are very distinct and nearly 

 equal and regular. Their plates are less convex and not so 

 large, about five corresponding to four in the row above. They 

 are broadly in contact serially, but the two rows are separated 

 by a regular row of large papular areas, like those above. 



Below the inferomarginals and closely joined to them and to 

 each other there are three or four rows of squarish interactinal 

 plates, so closely united and compactly granulated that their out- 

 lines are concealed. Their granules gradually become coarser 

 and angular near the adambulacral spines. 



The adambulacral plates are small and concealed by granules. 

 Each bears two unequal inner erect spines; both are flattened 

 and obtuse. The larger is more than twice as large as the other, 

 but only a little higher. Outside these, but close to them, and 

 alternating with them, is a single larger, obtuse, flattened, erect 

 spine, about twice as large as the larger inner ones, and about as 

 broad as high. These, like the inner ones, form a regular con- 

 tinuous row, very distinct from the adjacent granules. 



These rows continue to the jaw plates with but slight change, 



