KCHIXOIDHA. II, 5i 



fonuiiig the anterior ed>je (posterior series of the antero-lateral iiiterambulacra) are ratlier closelv 

 covered b\ pniiiary tubercles, not arrani^ed in distinct series. (Comp. Loven. I'ourtalesia. PI. I. 3). The 

 miliary tubercles are generall\- \er\ nunierons, especiall\- on the anterior end of the test. — One speci- 

 men is interestini;- in showing in considerable number the empty places of primary tubercles; tlie 

 places are distinctly seen, but covered with ])ignicnted skin, and it looks as if miliarv spines have 

 appeared in some of them. As mentioned above (sub Urrcliiuns jiansiaiixs. p. 41) Agassiz thinks 

 such cases a proof of the spines having been resorbed — I think it more probable that it is the result 

 of some damage undergone by the specimen. 



The primary spines are of a rather uniform length, the longest of tliem (the posterior ones of 

 those on the anterior series of plates of the antero-lateral ambulacra, in accordance with the size of 

 the tubercles) .scarcely reaching one third of the length of the test. They are slightlv curved, generallv 

 smooth, ending in a simple point. Tliose of the sternum are .somewhat flattened, widened at the i)oint. 

 The spines on the invaginated portion are short and very robust (Loven. Pourtalesia. PL \'. 36); lho.se 

 near the edge are longer and more slender, gracefully curved. The miliary spines are widened at the 

 point and curved, as figured b\- Wyv. Thomson (PI. LXX. 8); the clavuke of the fa.sciole essentially 

 as the miliary spines, the widened point only a little shorter and thicker. 



Spicules are almost totally wanting; sometimes, however, a very few irregular, branched rods 

 occur at the outer end of the tube-feet. The tip of the tube-feet, on the contrary, is enclosed by a 

 rather thick cap (or broad ring) of talcareous network (PI. VII. Fig. 21); this holds good, however, only 

 for those of the antero-lateral ambulacra, which are, upon the whole, rather well developed. In those 

 of the odd anterior ambulacrum such a calcareous cap is generally not found ; sometimes a few irreg- 

 ular spicules occur there, but mostl\- they are quite destitute of .spicules. 



Of pedicellaria; two kinds, viz. opliiceplialous and tridentate, were described and figured by 

 \V\v. Thomson, and two kinds, viz. ophicephalous and rostrate ( laternenformige> tridentate) b\- D6- 

 derlein (Echinoiden d. deutschen Tiefsee-Exped. p. 269). I have found these three forms; globiferous 

 pedicellaria; do not seem to occur. The rostrate pedicellarite (PI. XI. P~igs. 9 — 10,30) are rather conspicuous 

 and numerous; the head up to ca. 0-5""", more or less dark pigmented. They are generally threevalved, 

 but two- and fourvalved specimens occur. (For the description of the \'alves, comp. Doderlein, loc. 

 cit.) The elegantly shaped ophicephalous pedicellarise are likewise well described by Doderlein, 

 whilst Wyv. Thomson has given a pair of rather good figures of them; I give here onl\- figures 

 of isolated valves in front and side view (PL XI. Figs. 4, 7). — It mav be noticed that the narrow part 

 of the valves of these pedicellarije contains a small irregular cavity, which opens into the deej^ening 

 in the widened outer part. This is, otherwise, especialh' distinct on the ophicephalous pedicellaria of 

 Pourt. paradoxa figured PI. XI. Figs. 3, 6. I have not found the ophicephalous pedicellarite on all the 

 specimens. — The tridentate pedicellaria;, the form figured by Wyv. Thomson PI. LXX. Fig. 10, are 

 very small, with a short but distinct neck. The valves (PL XI. Fig. 8) are .simply leafshaped, the edge 

 of the outer part rather coarsely serrate. (That this form must be regarded as a tridentate, not a tri- 

 phyllous pedicellaria becomes evident from what is found in Pourt. hispida (comp. below p. 78); also 

 in Plexecliiuiis hirsiitits a quite similar tridentate pedicellaria occurs together with typical triphyllous 

 pedicellariie; comp. above p. 56.) 



