115 



mel with. The buccal plates are placed one a little outside the other. A lew pedi- 

 cellaiiæ are found on the buccal plates in larger specimens. The moutlislits are 

 small but rather sharp. 



The spines are smooth, short, those at the ambitus and just below being 

 the longest (about '/4 of the diameter of the test); towards the apical system they 

 become gradually shorter. Those round the actinostome are a little curved, not 

 widened at the point; they are beautifully red coloured and tipped with white. 



The globifcrous pedicellariæ (PI. VII. Fig. 8) do not present marked charac- 

 ters by which they may be distinguished from those of the other Gymnechiniis-specicfi. 

 There are glands on the stalk. „Claviform" ]iedicellariæ are also found. The tridentate 

 ])edicellariæ (PI. VII. Fig. 29) are very characteristic. The blade is narrow in the 

 lower part, with a more or less developed meshwork high up from the bottom uniting 

 the sides; the outer part is widened, the edges irregularly sinuate and finely serrate; 

 the edge of the lower part is smooth or with a few irregularly placed serrations. 

 The valves join only with the outer, widened part. Length of the head c. 05 mm. 

 The ophicephalous pedicellariæ (PI. VII. Fig. 41) do not present peculiar features; 

 the triphyllous ones (PI. VII. Fig. 3(1) have the blade rather widened, otherwise they are 

 of the common form. — The spha'ridiæ are smooth, of the usual form. — The spi- 

 cules of the globiferous pedicellariæ (PI. VII. Fig. 46) are bowshaped, with the ends 

 thickened. In the lubefeel a few bihamate spicules are found. The walls of the 

 intestine may contain some vei'y few small bihamate spicules; in the genital organs 

 I have seen none. 



The auricules are formed of two high, narrow processes, which do not 

 unite above, even in the largest sjiecimens. The dental ajiparatus is low and strongly 

 rounded below. 



The colour of the test is white, with a faint reddish tint, the red colour of 

 the spines looking most delicate against the while ground colour. 



A considerable number of this beautiful little species was taken at 

 several localities in the Gulf of Siam: Koh Kam, 5 10 fathoms, Koh Kram, 

 30 faths., Koh Mesan, 5—15 faths., Koh Kahdat, 1—10 laths., Koh Mak, 5—6 faths., 

 all on hard bottom, .sand, gravel or stone. Further a few specimens have been 

 taken at Singapore by Mr. Gad, 1903. A great number of them carried an empty 

 bivalve shell on them, held rather firmly by the abactinal suckers, the whole 

 animal being thereby ({uite covered, when seen from above. From the Maldive 

 Islands I have seen 3 small specimens (in the collection sent me for examination 

 from Profs. F. Harmer), which appear to belong to this species, but as tridentate 

 pedicellariæ could not be found , I dare not affirm that they belong to this 

 species. The colour of the spines is faint violet. (They were named Temno- 

 pleurus'}) 



In the „Ingolf"-Echinoidea (p. 110) I have written of Gymnech. darnleyensis 

 that the ocular plates are not excluded from the periproct, according to infor- 



15* 



