ECHINOIDKA. I. 



io 3 



2—4 teeth <ni cither side. The basal part has somewhat projecting outer corners. The ophicephalous 

 pedieellaria; are of the common form, the tripliyllous ones resemble those of Ech. margaritaceus. 

 Agassiz says, but wrongly, that only two kinds of pedieellariie are found in this species, one small- 

 headed, long-stemmed, the other short-stemmed with a conical bead . He gives, however, no figures 

 of them. Unfortunately I can give no informations as to the peristome, as I forgot to examine it 

 during my stay at British Museum. Neither can I tell whether the actiual primary spines are curved 

 at the point. Primary spines are found on all the ambulacral plates; all the ocular plates are shut 

 off from the periproct. The central plate little conspicuous. The spicules bihamate, numerous. 



Echinus Neumayeri Meissner is also to be classed with these species, but is, however, rather 

 sharply distinguished by several characters. In the description by Meissner (285) only the apical area 

 is more thoroughly examined; as the type specimen has been sent me for closer examination, I am 

 able to call attention to several other characteristic features of this species. A primary tubercle is only 

 found in every other ambulacral plate. Unfortunately all the primary spines are broken, so that 

 nothing can be said as to their length, or whether the actinal ones are curved at the point — what 

 is probable. The secondary spines are rather coarse, not fine, silky, as in the two preceding species; 

 they are, however, finely serrate. Three of the ocular plates reach to the periproct, as observed by 

 Meissner; no conspicuous central plate is found. The apical area of the type specimen is, no doubt, 

 abnormal, two of the genital plates being coalesced, and the adjoining one uncommonly broad; by this 

 arrangement the two ocular plates at these genital plates are situated opposite to the latter, and not, 

 as is elsewhere the case, opposite to the interspaces between them. (See the figure of Meissner. 

 Op. cit. p. 12). The buccal membrane contains numerous small fenestrated plates inside of the buccal 

 plates, outside of these it is almost naked, only with quite few, small fenestrated plates. Spines are 

 found on the buccal plates. The globiferous pedicellarise (PL XIX. Fig. 14) recall those of Ech. kor- 

 ridus very much, but the outer corners of the basal part are somewhat more conspicuous, and the 

 edges of the blade are connected by cross-beams; there are 1 — 1 or 1 — 2 lateral teeth. The tridentate 

 pedicellarise (PI. XX. Fig. 11) resemble those of Ech. margaritaceus, as is also the case with the tripliyl- 

 lous ones (PI. XX. Fig. 7); the ophicephalous ones of the common form. The spicules bihamate, very 

 few; I have only seen a few in the buccal membrane, none in the tube feet. 



Echinus ))iagcllanicns Phil. To the descriptions of this species by Philip pi and Agassiz the 

 following informations must be added. A primary tubercle is found on all the ambulacral plates; the 

 actinal primary spines are curved at the point, the secondary spines are coarse as in Ech. Neumayeri 

 and almost smooth. The buccal membrane is quite naked both inside and outside of the buccal plates, 

 and no spines seem to be found on these. The periproct is small, covered by a few, rather large plates, 

 without distinct central plate; generally one ocular plate reaches to the periproct, as observed by 

 Agassiz. The globiferous pedicellarige (PI. XIX. Fig. 23) chiefiy as in Ech. margaritaceus, with 1—2 

 teeth on either side. The tridentate pedicellarise (PI. XIX Figs. 11, 17), which are (always?) very small, 

 o-5 mm , are rather different from those of the other species; in the outer part where the valves join, tin- 

 edge is finely serrate, in the lower part it is smooth, but rather thick; no net of meshes at the 

 bottom. The valves are apart for a rather long space, but the slit between them is quite narrow. 

 The ophicephalous and triphyllous pedicellariee of the common form. The spicules bihamate, numerous. 



