REPORT ON THE ECHINOIDEA MORTENSEN 



255 



surface between the ridges being distinctly furrowed. The upper 

 primaries carry in their basal part 4 to 6 distant, larger spinules on 

 the adapical side (though not very distinctly shown in the figures). 

 The collar is short, 2-3 mm. in length. The oral primaries are of the 

 usual form, slender, and not very conspicuous. In the present spec- 

 imen only the three proximal ones have the shape of oral spines. 

 The secondary spines are scarcely 4 mm. long, rather broad, flat, not 

 excavated, often ending in three small points. (PI. 77, fig. 8.) They 

 are appressed toward the base of the primaries. Those of the ambu- 

 lacra are about 3 mm. long, narrow, but flattened, and not setaceous. 



The large triden- 

 tate pedicellariae are 

 short, robust, with 

 the head scarcely 

 more than 2 mm. 

 long. The valves (pi. 

 77, fig. 5) are broad, 

 nearly triangular, 

 with the blade filled 

 with a close mesh- 

 work but with a 

 shallow depression 

 above the apophy- 

 sis. The small tri- 

 dent ate pedicella- 

 riae (pi. 7 7, figs. 

 6-7) are shorter and 

 broader than is usual 

 in this genus, with 

 some longer teeth at 

 the point of the blade. The spicules of the tube feet are not charac- 

 teristic, being of the usual form. 



The color of test and secondary spines is brown, the primary 

 spines being w T hite, excepting the collar, which is brownish, like the 

 secondaries. 



Remarks. — This specimen shows some resemblances to the form 

 referred to by de Meijere, 4 to Histocidaris misahiensis (Yoshiwara). 

 Especially the presence of some larger spinules on the adapical side 

 at the base of the upper primary spines is a conspicuous point of 

 resemblance. But in other regards, as in the very sparse tubercula- 

 tion of the apical system, the shape of the secondary spines, and the 

 pedicellariae, it differs so markedly from that form (which is other- 

 wise entirely difl'erent from the true H. misahiensis of Yoshiwara, 



Fig. 8.— Apical system of Histocidaris, spf.cies. XC 



J Siboga Echinoidea, p. 27, pi. 2, figs. 15, 16; pi. 12, figs. Ill, 142. 



