ECHINOIUEA. 11. 



53 



liere; it is, however, evidently not very correctly drawn. 1 ha\e .seen nothing resembling the fignre.s 

 I'l. XLIII. lo— ii; they probably represent only small s])ecimens of this kind of tridentate pedicellariae. 

 The .second form (PL X. Figs, i, 4, 24, 28, 29) is coarser and the form of the blade often .somewhat irre- 

 gular; it has generalU' some very irregular nieslnvork. This kind of pedicellariae is found on the 

 actinal .side, and especially on the peristome, even in the month they are quite crowded, reaching 

 some wav up the oesophagus; those found here are generally more irregular than tliose on the out- 

 side of the test (PI. X. Fig.s. 28 — 29). — It is probably this second form of tridentate pedicellariae which 

 is figured in PI. XLIII. Fig. 12 of the Challenger -Ech. under the name of Clypeastroid-like pcdi- 

 cellaria; the valve represented in PI. XLV. F'ig. 35 as belonging to this form is certainly that of an 

 ophicephalous pedicellaria, but it seems very unlikely th.at it can belong to this form ; the figure 

 PI. XLIII. 12 does not seem so very bad, as it would be in case the \alve did really belong to it — 

 and on the other hand, this coarse form of tridentate pedicellariae is generally invested with a rather 

 thick, brown skin, so that by a superficial examination not much more is seen than the figure cited 

 shows. — The ophicephalous pedicellarise are like those of P. Rathbiuii. the valves being low and 

 rather broad. The PI. XLV. Fig. 35 of the Challenger -Ech. gives a rather good representation thereof. 

 The fio-ures PI. XXX\'. 17 — 18 may perhaps also represent the ophicephalous pedicellaria;; they are 

 however, so crudelv made that it is quite useless to speculate on what they are meant to represent. 

 — The triphvUons pedicellarite are like those of P. Rathbuni. The supporting rods of the filaments of 

 the actinal tube-feet are like those of Urechhms; spicules I have not seen. The spines evidently deserve 

 to be carefullv studied; m>- preparations however do not allow me to give more than a few remarks 

 thereon. The onlv (broken) primary spine I have seen does not agree with the figure and description 

 given bv Agassiz, it is curved and finely undulated along the longitudinal ridge-S. Club-shaped spines 

 are found at the actinostome as in Urrcli. iiarcsianus. 



To the Urrc/iiiitda- is further referred the genus Calymnc. The figures given in the Challenger > 

 Report do not allow one to see the real structure of the anterior paired 

 interambulacra; finding that this was an important character for the classi- 

 fication of the Meridosternata (viz. whether the second plate of these 

 interambulacra is single or double — Comp. below p. 85), I carefully examined 

 the fragments of the type specimens in the British Museum in this regard 

 and found that the first plate is in contact with two of the following plates. 

 The unusual size of the actinal ambulacral plates makes it a little diffi- 

 cult to .see the real structure in the poor fragments preserved; but the 



pores of the ambulacral plates are distinct and leave no doubt of the ^f-^- P^;' "'!''; ^'""'''' '^J^'^ 

 i^ ' of the test of Calymne relicta. 



morphological value of the plates (Fig. 7). (The figure is made after a 



.sketch taken without camera and thus cannot claim to be quite correct as regards the outline of the 



plates; but in the main features it is correct.) 



The apical system is certainly not very correctly given in the Fig. 2. PI. XXXI\' of the 

 <Challenger:>-Ech. The two anterior genital plates with the madreporite seem to be confluent, not forming 

 two (or three) separate plates as in that figure. Of the two posterior genital pores seen in this figure 



