ECHINOIDEA. II. 



distinct calcareous cap in the point of the tube-feet (PI. VII. Fig. 17), though not formed by one plate. 

 The spicules are of the usual form, lying in two close longitudinal series. 



Echinocrepis cuneata A. Ag. In this species the bivial ambulacra are evidently uninterrupted 

 (*Chall.-.-Ech. PI. XXXV. a. 10), as is also pointed out by de Meijere (Siboga-Ech. p. 168). In Pan. 

 Deep-Sea Ech.;> p. 147 Agassiz states that - the arrangement of the actinal plates of Echinocrepis 

 cuneata is, according to Loven (Pourtalesia. PI. VII. Fig. 53), much like that of Spatagocystis Chal- 



Icngeri which seems to mean that the bivial ambulacra are interrupted by the interambulacra i 



and 4. This can, however, not be deduced from the small fragment figured by Loven, and the figure 

 from the ChalL>-Ech. quoted above does not seem to be so very incorrect, as it would be, in case 

 the species really agreed with Spatagocystis in this respect. Also Loven states expressly (p. 17) that 

 he considers Echinocr. cuneata to differ in a marked manner* from P. Jcffreysi, laguncula etc. in 

 having the bivial ambulacra uninterrupted. Unfortunately the specimen in the British Museum does 

 not afford any solution of the question, the plastron not being preserved. The apical system ' is com- 

 pact, the postero-lateral (bivial) ambulacra not being separated from the rest of the apical system 

 through intercalated plates, as has been shown by Loven (On Pourtalesia. PL VII. Fig. 54); I may 

 further point out the fact that the dorsal plates of the odd interambulacrum are not paired, but alter- 

 nating (as seen in this same figure) evidently a more primitive condition. Of pedicellariae I have seen 

 only one kind, viz. tridentate. The small ones are of the common simple leafshaped form, with the 

 apophysis continuing into the edges of the blade; the larger form is figured in the Challenger -Re- 

 port PL XLV. Fig. 44, I have only to add that generally there is a wingshaped keel along the dorsal 

 side of the blade (PL X. Fig. 39). .The spicules are rather numerous, simple or triradiate. 



Ecliinocrepis setigera A. Ag. differs from E. cuneata in several important features. The bivial 

 ambulacra are interrupted on the actinal side by the postero-lateral interambulacra, and the apical 

 system is disconnected. I have found three kinds of pedicellariae (on some small fragments examined in 

 the U. S. National Museum), viz. tridentate, rostrate and ophicephalous. The tridentate pedicellariae are 

 of the common form, with simple leafshaped valves (only a small specimen seen). The rostrate pedi- 

 cellariae (PL X. Fig. 12) are more or less elongate, the outer edge finely serrate. (Perhaps this form is 

 not really the rostrate, but another kind of tridentate pedicellarise.) The ophicephalous pedicellariae 

 (PL X. Figs. 3, 33) are somewhat smaller and more longstalked than usual; otherwise they do not differ 



1 Agassiz (Panamic Deep-Sea Ech. p. 131) says that the plates of the apical system of Echinocrcpis are not as they 

 have been described by de Meijere; those of the bivium are well separated by the posterior lateral interarabulacra from 

 those of the trivium. There are the two posterior ocular plates, and the anterior ones are ankylosed, the oculars of the tri- 

 vium being lost and occupied by the madreporite. (Pis. 67. fig. 2; 69, figs. 3, 4) . Quite apart from the fact that Agassiz 

 here is in evident contradiction to his own statement (p. 146) that in Echinocrepis setigera the ocular plate can only be 

 traced in the odd anterior ambulacrum. In the crowding due to the intrusion of the intercalated and interambulacral plates 

 between the bivium and the trivium they ( evidently the other ocular plates ) have been pushed out of place or resorbed, 

 it may be stated that de Meijere's description (Siboga*>-Ech. p. 162) is quite correct, his description being based on 

 Loven 's Figure 54. PI. VII (On Pourtalesia), as expressly named, and it is Echinocrepis cuneata whose apical system is 

 described, as is also expressly said, not E. setigera, to which Agassiz refers. Further de Meijere remarks (p. 164! Nach 

 Agassiz' Figur (viz. PI. XIII. i of the Prelim. Report on the Albatross -Echini) scheint die von der Albatross-Expedition 

 erbeutete Echinocrepis setigera auch ein ebensolches, aus einander geriicktes Apicalsystem zu besitzen, wie Spatagocystis u. s. w. 

 und wtirde sich somit von E. cuneata scharf unterscheiden. De Meijere's description of the plates of Echinocrepis is thus 

 quite correct. 



II* 



