i ( HINOIDE \. II 



6l 



forming the anterior edge (posterior series of the antero-lateral interambulacra) arc rather closely 

 covered by primary tubercles, inn arranged in distinct series. (Comp. I. oven, l'oui talesia. PL I. 3). The 

 miliarv tubercles are generally very numerous, especially on the anterior end of the test. - One speci- 

 men is interesting in showing in considerable number the emptj places of primary tubercles; the 

 places are distinctly seen, but covered with pigmented skin, and it looks as if miliary spines have 

 appeared in some of them. As mentioned above (sub Urechinus naresianus, 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 them (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 slightly curved, generally 

 smooth, ending in a simple point. Those of the sternum are somewhat flattened, widened at the point. 

 The spines 011 the invaginated portion are short and very robust (Loven. Pourtalesia. PI. V. 36); those 

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

 point and curved, as figured by Wyv. Thomson (PI. LXX. 8); the clavuke of the fasciole 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 calcareous 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 mostly they are quite destitute of spicules. 



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

 \\ yv. Thomson, and two kinds, viz. ophicephalous and rostrate ( laterneiiforrnige tridentate) by D6- 

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

 pedicellaria: do not seem to occur. The rostrate pedicellarue (PI. XI. Figs. 9 — 10,30) are rather conspicuous 

 and numerous; the head up to ca. o-^ m "\ more or less dark pigmented. They are generally threevalved, 

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

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

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

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

 of the valves of these pedicellariae contains a small irregular cavity, which opens into the deepening 

 in the widened outer part. This is, otherwise, especially distinct on the ophicephalons pedicellaria of 

 Ponrt. paradoxa figured PL XI. Figs. 3, 6. I have not found the ophicephalous pedicellariae on all the 

 specimens. — The tridentate pedicellariae, the form figured by Wyv. Thomson PL 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. liispida (comp. below p. 78); also 

 in Plexccliinus hirsntus a quite similar tridentate pedicellaria occurs together with typical triphyllous 

 pedicellariae; comp. above p. 56.) 



