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 pedicellariæ have been carefully described and figured in the »Ingolf» Echi- 
noidea I, p. 122. PI. 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- 
cellariæ (PI. XVI Fig. 1 7) 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 pedicellariæ 
(PL XVI. Figs. 2, 5) are generally as here represented; the two figures given in the 
»Ingolf» Echinoidea I. PL 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 serrations at the end of the blade are much less 
tooth-like than in the Fig. 18 of the Tngolf» Ech., and there is no distinct keel in 
the middle of the blade. The ophicephalous pedicellariæ (PL XVI. Fig. 14) have 
rather lengthened valves with the apophysis widened over the blade, not forming a 
keel. The triphyllous pedicellariæ (PL XVI. Fig. 16) are small, with the blade 
rounded, the edge not serrated. 
The sphæridiæ (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 10th 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. 
