144 



ECHINOIDEA. I. 



small plates; here and here a tubercle may be fomid on a somewhat larger plate. Nearest to the 

 anal opening tlie small plates are a little lengthened. 



The buccal membrane commonh' richh' provided with large, simple fenestrated plates as in 

 Ec/l Alexandria those inside of the buccal plates also as in this species. Bihamate spicules may be 

 found in rather great number among the fenestrated plates. A few of the plates outside of the buccal 

 plates are larger and somewhat complicate, and carry pedicellarise. No spines on the buccal plates. 



The spines of a middle length, 1/2 — ^,'3 of the diameter of the test, rather strong; they are 

 largest at the ambitus, but decrease generally only little towards the apical area. The actinal prim- 

 ary spines may be truncate and flat at the point (not constantly), not irregularh' widened as in 

 Ech. acuhis. 



The pedicellarise are generally very numerous, especially the ophicephalous ones. The globi- 

 ferous ones (PI. XVIII. Figs. 2 — 3) have most frequently 2—3 teeth on either side of the blade, some- 

 times 3 or only one on one side, two on the other. The basal part has often a few indentations in 

 the edge, but this is no constant feature. The stalk is rather strong and may at the upper end have 

 some thorns directed downward (PI. XX. Fig. 23). The tridentate pedicellarise (PI. XMTI. Figs. 22, 26. 

 PI. XX. Fig. 9): the valves rather broad, a little widened at the point, where they join; the edge is here 

 rather sinuate, in the other part it is straight, thick, and set with small teeth forming somewhat 

 irregular transverse series. There is a rather well developed mesh-work at the bottom of the blade. 

 — Together with this form is often found a smaller one (PI. XX. Fig. 9), wliere the blade is almost 

 quite flat and rather abrupth truncate at the point, without mesh-work. In some specimens onl\' this 

 form is found. Transitional forms between this form and the larger one are found, so that it cannot 

 be regarded as another kind than the larger form. — The ophicephalous (PI. XIX. Fig. 10) and the 

 triph\Ilous pedicellaria' (PI. XX. F'ig. 22) show no marked peculiarities. — The sphseridise (PI. XIX. 

 Fig. 26) are generalh- somewhat grooved and tliorn\-; the grooves often form rather distinct longi- 

 tudinal series. The spicules (PI. XX. F'ig. 8) are small and rather varying in form. They are prett>- 

 numerous in the tube feet and gills; in the skin round the base of the spines some spicules are 

 generally found, and sometimes a few are found in the stalks of the pedicellaria; (the globifer- 

 ous ones). 



The ty])ical coloration is as on PI. III. P'ig. 4: purple, white-tipped spines; the test white, 

 slight!)' rosy round tlie apical area (PI. I. Fig. 3). In some of the specimens in lu\nd this colour, liow- 

 ever, is only slightly indicated; some are quite white, others have only a slight yellowish red tint 

 aroiuul llu- apical area or onh- at the base of some of tlic prinuiry tul>ercles on the abactiual side. lu 

 one specimen the test is of a fine lilac colour (PI. I. P'ig. 2). 



cingolf St. I (62" 30' N. L. 8"2i'\V. L. 142 fatliom.s, Sand, Shells. Bottom temp, y"" 8). i spec. 



- - 47 (61° 32' - 13° 40' - 950 - Mud. - 3° I). 3 - 



- — 52 (63° 57' — 13° 32' — 420 — ? — f 2). 2 — 



- -54 (63° 08' - 15° 40' _ 691 - ? - 4° 2). 6 - 



This species is indigenous in tlie sublittoral-archil)enthal zone of the northern Atlantic, both 

 at the Huropean and American side, as well as south of Iceland, and in the sea along Norwa\-; it is 

 found on ca. 50—950 fathoms. The statement that it goes down to 1350 fathoms ((.Challenger - 



