28 



ihe actinogonidiate Echinodenns of the Maldive and Laccadive Islands. As it is 

 of importance to know tin- stiuctnrc ol' the young stages of the species, I shall 

 make some remarks on this specimen. 



Diameter 22 mm., height 8 mm., apical area 7,5 mm., peristome 5 mm. 

 The naked part of the intcranibulacra is somewhat sunken, the ambulacra and the 

 adjacent part of the interambulacra correspondingly raised. The u]ipermost one of 

 the large interambulacral tubercles in the outer series is found on the ;^rd or 4th 

 ]ilate from above (the small incomplete plates at the uj)per end not included); the 

 next series begins on the following plate. Only two series of large tubercles are 

 found on each side of the area. A series of secondary tubercles along the inner 

 side of the large tubercles of the outer series continues until the apical system. A 

 primary ambulacral tubercle is found on all the plates until the apex, except, of 

 course, on the uppermost young plates. The apical system does not differ from 

 that of the larger specimens; the genital ])apilla is well developed. The actinal side 

 presents the features typical for the species. The pores are arranged in a quite 

 regular single series, not crowded at the ambitus, and not so distant in the granu- 

 lated part as in the large specimens; on the abactinal side they form rather distinct 

 arcs; they are almost equally large over the whole test. Pedicellariæ and spicules 

 as in the large specimens, only the spicules more numerous. The colour of test and 

 spines is whitish; there is a small violet spot at the base of the spines, on the side 

 turning towards the top. Blue spots as in large specimens. 



The distribution of this species is thus shown to be from the Maldive Islands 

 to New Guinea. 



Among some Echinids from Japan (Sagami-See, i3() fathoms, coll. Owstkn), 

 sent to me for examination from the Hamburg-Museum , I find two Astropyga-Uke 

 specimens (of 71 and 76 mm. diameter), which through the arrangement of the 

 pores on the actinal side in a single series prove to belong to the genus Chœtodiadema. 

 They are, as regards their habitus, very similar to C. cjraniilatiim , from which 

 species, however, they differ so much in several characters that they must form 

 a separate species, for which I propose the name Chætodiadenia japonicum n. sp. 



The form of the test (PI. II. Figs. 16, 19) is like that of Ch. cjraimlatum. The 

 abactinal side agrees with that species as regards the tuberculation; however, it 

 looks rather ditïerent owing to the blue spots along the outer edge of the inter- 

 ambulacra being united so as lo form a continuous line from the ambitus to the 

 a|)ical system; at the iq)per end the two lines of each area diverge, bending towards 

 the ambulacra, making thus a very characteristic design (PI. II. Fig. 16.). In the 

 siiecimen figured from the abactinal side the thick skin of these lines is rubbed 

 off, the white plating below thus making the lines miu'h more prominent than 

 when the dark skin is preserved. No blue spots are seen on the apical system. 



The actinal side presents more considerable diflerences from gramilatum. 

 The tubercles diminish more graduallv in size from the ambitus towards the 



