222 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



times flattened, curved, and entire, slightly notched or even serrate, but frequently- 

 thick, straight, and more or less smooth ; secondaries flat, those on ambulacra quite 

 narrow. Large globiferous sometimes, and tridentate pedicellariae always, want- 

 ing ; small ones sometimes with, more often without, end-tooth on valves. 



The above diagnosis of this interesting monotypic genus is based on a large 

 series of specimens, 11-40 mm. h.d., which admits of little question of the iden- 

 tity of Doderlein's St. japonica and Yoshiwara's C. tenuispimis. Some of the 

 peculiarities are given by those writers in their original descriptions of the only 

 species, which they regarded as a Stereocidaris. While its nearest relatives are 

 probably to be found iu that genus, it is quite distinct from them and is well 

 entitled to generic rank. For a full discussion of this genus and its type species, 

 see A. Agassiz and Clark, 1907, Bull. M. C Z., 51, p. 112-114. 



Anomocidaris japonica. 



Dorocidaris japonica Doderlein, 1885, Arch. Naturg., 51 Jhrg., 1, p. 76. 

 Stereocidaris japonica Doderlein, 1887, Jap. Seeigel, p. 34. 



Cidaris (Stereocidaris) tenuispinus Yoshiwara, 1898, Ann. Zool. Jap. 2, pt. 2, p. 57. 

 Anomocidaris tenuispina A. Agassiz and Clark, 1907, Haw. Pac. Ech. Cid., p. 30. 

 Anomocidaris japonica. A. Agassiz and Clark, 1907, Prelim. Rep. Albatross 1906 

 Ech., Bull. M. C. Z., 51, p. 112-114. 



Plate 31, figs. 5-8, Haw. Pac. Ech. Cid., A. Agassiz and Clark, 1907. Plate 3, 



Jap. Seeigel, Doderlein, 1887. 



The only known specimens of this species have been taken in Japanese waters, 

 in 40-284 fths. The largest specimen is 40 mm. h. d. The color of test and sec- 

 ondaries is commonly some shade of brown, often reddish, sometimes greenish, 

 while the primaries are grayish or brownish, often with a decidedly olive-green 

 tinge, rarely rosy-reddish ; the neck is brown, usually polished and shining. 



ACANTHOCIDARIS. 



Acanthocidaris Mortensen, 1903, Ingolf-Exp. Ech., 1, p. 21. 



Test high, .60-.70 h. d. ; coronal plates 7 or 8 ; areolae not at all sunken and very 

 distinct, even actinally ; median interambulacral area somewhat sunken and bare 

 along vertical suture ; ambulacra about .25 of interambulacra ; poriferous zones 

 little sunken ; each ambulacral plate slightly curved, with a single large tubercle 

 near upper margin of median portion, a much smaller one near lower margin half- 

 way to inner end, and a very minute one (which usually carries a pedicellaria) just 

 beneath largest ; this arrangement is remarkably constant, regardless of age and 

 size; it is well shown in a specimen 9 mm. h. d., and is not essentially different in 

 one 52 mm. h. d. ; in some very large specimens, however, another small secondary 

 tubercle may be borne on inner end of plate ; median vertical suture usually visible, 

 but there is no noticeable median bare strip ; pores oblique much as in Cidaris. 

 Abactinal system about .45 h. d., very flat; peculiar in that all oculars are broadly 



