AGASSIZ AND CLARK : REPORT ON ECHINI. 113 



figures with Yoshiwara's description and with our numerous specimens, ranging 

 from 11 to 40 mm. in diameter, has satisfied us that japonica and tenuispina are 

 identical. But we retain the genus Anomocidaris on account of the bare abactinal 

 surface, which is different from that of any other Echiuoid in the absence of pri- 

 mary tubercles on the upper coronal plates. In small examples of Stereocidaris 

 and other Cidaridae, on the youngest coronal plate, next to the abactinal system, 

 a primary tubercle is formed which increases in size with the growth of the plate 

 and sooner or later bears a primary spine ; in the adult, therefore, the uppermost 

 coronal plate has an imperfect tubercle, the second has a more perfect tubercle 

 which usually carries a spine and the third always has a primary spine. In small 

 examples of Anomocidaris (11 mm. in diameter), there are six coronal plates, of 

 which the uppermost has a well-formed tubercle and the other five carry primary 

 spines, that on the second plate being the longest. As the animal grows, addi- 

 tional plates form abactinally but these have no primary tubercles and often 

 scarcely an areola, while the spineless tubercle on the plate above the longest spine 

 appears to be gradually more or less resorbed. In large specimens there are 

 usually eight, aud may be as many as nine, coronal plates, of which the five or 

 six nearest the actinostome carry primaries, while the remaining two or three have 

 no tubercles and only indications of small areolae. As the actinal coronal plates 

 are small and crowded while those on the abactiual surface are very large, the 

 spines are all actinal in position, except the longest which are just at the ambitus. 

 Consequently the abactinal surface is extraordinarily bare, and the genus Anomo- 

 cidaris is therefore easily recognized. — The primary spines are more slender than 

 in Stereocidaris but show considerable diversity. They frequently taper to the 

 very tip but are often more or less flaring there, and occasionally, in large speci- 

 mens, are distinctly flattened and slightly widened at the extremity. They are 

 grayish or brownish in color, often with a decidedly olive-green, very rarely a 

 rosy-red, cast ; the neck is brown, usually polished and shining, while the narrow 

 collar is commonly dirty whitish, but may be darker than the neck. The pri- 

 maries around the actinostome show the greatest diversity. In the smallest 

 specimens, they are white, flat, curved at the tip, and distinctly serrate, exactly as 

 Doderlein figures them {ox japonica, but in the large specimens they are dull gray, 

 but little flattened, not at all curved, aud with no trace of serrations. Inter- 

 mediate conditions between the two extremes are common, and the differences 

 appear to be due to age. — The pedicellariae are equally variable, for on some 

 specimens, the large globiferous, such as Doderlein figures for japonica, are very 

 common, on others they are rare and on others they seem to be wholly wanting. 

 The diversity of the small globiferous pedicellariae has already been shown by us 

 in " Hawaiian and Pacific Echini : Cidaridae," Plate 11, figs. 6-12 and Plate 12, 

 fig. 18. They intergrade with the large globiferous pedicellariae quite impercep- 

 tibly. Tridentate pedicellariae appear to be always absent. — The color of the 

 test and small spines also reveals some diversity. The test is commonly reddish- 

 brown, but it may be gi-eenish or not infrequently dirty whitish ; it is almost 

 always darkest abactinally. The small spines are usually distinctly greenish, 

 more or less decidedly lighter on the edges than at the middle, but they may be 

 vol. li. — No. 5 8 



