ECHINOIDEA. I. 



I 1> 



all events, deserves a closer examination. There is, however, one feature left, from which important 

 contributions to the classification may he expected, viz. the larval forms. As almost all the species 

 belonging here, are littoral forms, they may all be supposed to have pelagic larvae, and they will, no 

 doubt, show a great richness in forms. That the larva of Spharechinus is so different from those of 

 Echinus 1 ) indicates, at all events, that very interesting things may be found here. 



Fam. Echinidae. 



Subfam. Parechininae. 

 n. Parechinus miliaris (Mull.). 



PI. II. Fig. 7. PI. XV. Figs. 6— 7, 11. PI. XVI. Fig. 15. PI. XVII. Figs. 1 — 2, 7—8, [O— II, 14— '5. 22-28. 



Principal svnouvnis: Echinus miliaris Mull. 



Psammechinus miliaris (Lamk.). 

 Echinus saxatilis O. F. Mull. 

 7'irei/s Dub. Kor. 



Principal literature: Diibeu & Kor en: Ofversigt af Skandinaviens Kchiuodermer. p. 274. 

 Agassiz: Revision of Echini, p. 495. — Hoyle: Revised List of Brit. Echinoidea (202). p. 417. - 

 Bell: Catalogue of Brit. Echinoderms. p. 150. With regard to the other extensive literature the reader 

 is especially referred to Bell's Catalogue. 



It is not necessary to give a thorough description of this well known species, I shall only 

 refer to the works cited above. On PI. II. Fig. 7 is given a coloured figure of the animal; with regard 

 to the test I shall refer to PI. XV. Figs. 6— 7, 11, where the apical area, an ambulacral and an interambu- 

 lacral area are represented. From these figures it is clearly seen that the secondary tubercles form 

 no regular longitudinal or transverse series, and that a primary tubercle is found on all the ambu- 

 lacral plates. The buccal membrane is richly provided with large, thick, irregular plates, between 

 which the naked skin is seen, especially on dried specimens; they are constructed as usual (PI. XVI. 

 Fig. 15; the figure represents one of the simplest plates from the outer edge of the peristome), con- 

 trarv to what is the fact in P. microtuberculatus (PI. XVI. Fig. 14) where they consist of a compact, 

 greenish calcareous mass with funnel-shaped holes. The plates inside of the buccal plates are some- 

 what smaller than those outside and constructed in a far simpler way; they consist only of one layer 

 with some knobs on the upper side. The buccal plates carry numerous pedicellarise, but no spines. 

 The gills contain small irregular calcareous plates. 



The pedicellaria;. The globiferous pedicellarise (PL XVII. Figs. 1, 7, 23—24) are generally exceed- 

 ingly numerous, and form, as it were, a dense, white flue, especially on the abactinal side. The blade 

 is rather broad and flat, and the edges not connected by cross-beams across the inside. The edges are 

 not thickened, and project into — generally - 7—8 long, somewhat irregular indentations; the number 

 may vary between 5 and 10. There are often some more on one side than on the other. The stalk 



M Tli. Mortensen: Die Echinodermenlarven der Plankton-Expedition. Ergebn. d. Plankton-Exped. d. Humboldt- 

 stiftung. II. J. 1S9S. 



