146 R. Ratlibun — List of the Brazilian Echinoderras. 



very much broader than the above, but not much longer, clavate in 

 general form, with compressed tips, not arranged regularly in longi- 

 tudinal rows, but in short, slightly oblique series of two, seldom 

 three, spines. Between the ventral and adambulacral rows of spines 

 the intervening space is very narrow, but the ventral anxl lateral rows 

 are widely separated. The lateral and dorsal spines are all of sub- 

 equal size, very small and short, al>out one-half as long as the adam- 

 bulacral or even shorter, cylindrical, or slightly tapering, and with 

 truncate, rounded ends. First above the ventrals comes a single 

 row of these spines, rather widely separated, and arranged one to a 

 plate, seldom two, with sometimes a short lower row, of six or seven 

 smaller spines, near the middle of the arm. Above the first lateral 

 rows of each side, we can distinguish in all five longitudinal series of 

 spines, including the median dorsal one. In these series the spines 

 are not generally regularly placed, but we can make out a certain 

 arrangement among them. The first series consists usually of two 

 rows of alternating spines, distinct neai'ly or quite to the tip of arm. 

 The second series, toward the disk, is made up of successive, irregu- 

 lar or slightly curved, transverse rows of four or five spines, with an 

 intervening spine to connect the several rows ; farther out the series 

 becomes reduced to a single, irregular, longitudinal row of spines. 

 The median dorsal series is formed of similar transverse rows of about 

 five spines each, arranged irregularly in the shape of a very broad V, 

 with the angle turned toward the disk; toward the tip there are only 

 two or three spines to a group. Near the disk there are many addi- 

 tional spines scattered over the arms, more or less obscuring the 

 above arrangement. The spines of the disk are similar in character 

 to those of the rays, and of the same size or slightly smaller ; they are 

 closely arranged but without order. 



The major pedicellarioe are very large and numerous, being scat- 

 tered over the entire surface of the rays and disk. Where perfectly 

 preserved, they are elongate triangular in outline, with strongly 

 curved base, and are about two-thirds as broad as long ; they often 

 appear ovate in outline. They vary in size, many being only one- 

 half or two-thirds as long as others. The larger ones equal or 

 slightly exceed the lateral and dorsal spines in length, and are very 

 much broader. Everywhere above the first lateral rows of spines, 

 they are about uniformly distributed, ranging most commonly along 

 the edges of the plates. Between the ventral and lateral rows of 

 spines, they are much more numerous, being esjaecially abundant 

 just above the bases of the ventral spines. They also occur, but more 



