KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 58. N:0 9. 19 



curved and a little widened towards the point. The miliary spines are ca. 0,4—0,5 mm 

 long, smooth or slightly serrate, with a small crown; the margin of the component 

 rods without indentations (PI. V, Fig. 27). 



Of pedicellariae only two sorts are found, viz. globiferous and triphyllous. The 

 globiferous pedicellariae (PI. V, Figs. 16, 20, 28) have long, tubeshaped, curved val- 

 ves, ending in a simple point, on the outer side of which is seen a fine opening. 

 On each side of the apophysis there is a large hole; evidently the poison glands 

 open through these holes into the tube, the poison being then emptied through the 

 opening on the endtooth. As seen in PI. V, Fig. 28, there is an inner sac in 

 connection Avith each hole, there being thus a pair of such sacs for each valve. 

 Probably this inner sac is only the lumen of the gland, filled with the secretion. 

 The outer part of the poison gland is more threaded in structure, probably on account 

 of the presence of muscle fibres; the exact structure, as well as the exact limit down- 

 wards of the gland could not be ascertained on the material available. • — The stalk 

 of the globiferous pedicellariae is a rather thick, finely fenestrated tube; there is no 

 neck. The biphyllous pedicellariae (PI. V, Fig. 13) have the valves provided with long 

 teeth at the point, these teeth interlacing, when the valves close. 



The tubefeet have a very small calcareous ring (PI. V, Fig. 12), consisting of 

 three small, elegantly shaped, fairly regularly branching plates, and three alternating 

 small, simple spicules below forming a ring, after the usual type. In each ambula- 

 crum there is a single pair of somewhat larger tubefeet at the border of the peri- 

 stome, corresponding to what obtains in Echinocyamus (»Ingolf »-Echinoidea II, p. 29, 

 PI. XII, Figs. 26 — 27). I have found no calcareous ring in these oral tubefeet. 



The presence of interambulacral series of tubefeet is a feature of considerable 

 interest, not hitherto noticed in the Fibularia's. It is, however, not a feature pecxi- 

 liar to the present species. I have found it quite distinct in another species (as yet 

 undetermined), which I have collected in the Gulf of Siam, and I think I can discern 

 such meridians of interradial pores also in Fibularia craniolans (only more or less 

 worn tests of this species are available). It may then perhaps prove to be a cha- 

 racter of generic value. The number of pores in the madreporic plate, on the other 

 hand, certainly is a character of specific value. In F. craniolaris there is only one 

 large, transversely elongated pore; the same is the case in F. cribellum De Meijerk, 

 while in the species from Siam, mentioned above, there are about 8 small pores. 

 This will then evidently prove a feature of considerable value for distinguishing the 

 species of this genus. 



Hitherto globiferous pedicellariae were totally unknown in the Clypeastrina. 

 It is then a very interesting fact that they have been discovered in this species, a 

 fact which is of no small importance for the discussion of the ancestry of the whole 

 group of the Clypeastrina. I shall, however, not enter on this very interesting pro- 

 blem at present. I may mention here that I have found globiferous pedicellariae 

 of the same structure also in the above mentioned Fibular ia-STpecics from the Gulf 

 of Siam; it would then appear that these pedicellariae are a characteristic of the 

 genus Fibularia. 



