Bd. VI: 4) THE ECHINOIDEA. 55 



The spines are upon the whole short and coarse; but the primary spines are 

 generally considerably longer and stouter than the secondary ones, thus being very 

 prominent, though short in comparison with the diameter of the test (PL VIII). 

 They are somewhat tapering, but not pointed; they are finely striated longitudinally, 

 otherwise smooth. The same also holds good for the smaller spines. The colour 

 of the spines is olive green, sometimes with a brownish tint. According to AgassIZ 

 (Rev. of Ech. p. 439) they are tipped with white; this is, however, not the case in 

 the specimens at my disposal. 



Spicules are extremely scarce in the tubefeet, only very seldom a single one of 

 the usual bihamate type occurring below the sucking disk. The walls of the intestine 

 likewise are devoid of spicules, whereas the genital organs contain rather numerous 

 fine, bihamate spicules. Also the gills contain some few bihamate spicules, mainly 

 in the outer branchlets, while in their lower part the usual fenestrate plates occur. 



The pedicellarise have been carefully described and figured in the »Ingolfa Echi- 

 noidea I, p. 122. PL XVII. Figs. 5, 12 and 18, to which work I may refer. I shall 

 here only give a few supplementary figures and remarks. The globiferous pedi- 

 cellarise (PL XVI Fig. 17) are characteristic in having a distinct neck, in which only 

 longitudinal muscles are found. The valves are as figured in the »Ingolf- Echinoi- 

 dea. I. PL XVII. Fig. 5, though sometimes more irregular; the upper end of the 

 apophysis may sometimes reach nearly to the edge. The tridentate pedicellariae 

 (PL XVI. Figs. 2, 5) are generally as here represented; the two figures given in the 

 >Ingolf» Echinoidea I. PI. XVII. Figs. 12 and 18 represent the extreme forms, the 

 former the small and less differentiated, the latter the largest and most differentiated 

 form. In those figured here the serration's at the end of the blade are much less 

 tooth-like than in the F'ig. 18 of the >Ingolf» Ech., and there is no distinct keel in 

 the middle of the blade. The ophicephalous pedicellariœ (PL XVI. Fig. 14) have 

 rather lengthened valves with the apophysis widened over the blade, not forming a 

 keel. The triphyllous pedicellariœ (PL XVI. Fig. 16) are small, with the blade 

 rounded, the edge not serrated. 



The sphœridia; (PL XVI. Fig. 4) are of the usual elongate oval shape, finely 

 thorny. They are not very numerous, only about 20 being counted in each series 

 in the larger specimens; they continue until ca. the loth ambulacral plate. 



The test is beautifully coloured: the median part of the ambulacra and inter- 

 ambulacra, between the two series of primary tubercles, is of a prominent reddish- 

 violet colour, on the whole abactinal side, the colour gradually disappearing on the 

 actinal side, though it may sometimes be traced almost to the actinostome. The 

 tubercles are white. The pore areas are of a light greenish colour, the outer edge 

 of the interambulacra of a darker green colour. The apical plates are of the same 

 red colour as the median part of the ambulacra and interambulacra. 



