CASSIDULID^. 



117 



they are examined on the abactinal side (PI. 52, fig. ]). The intrusion or 

 flow of the anal plates into the interambiilacral system of the Echinothiiriae 

 is well illustrated in A. conaceum. Though this seems so absurd to Dr. 

 Mortensen, yet Loven^ has suggested something of the j'ame kind as possible 

 when comparing a Collyrites to a Culcita-like starfish. 



PETALOSTTCHA Haeckel. 



CASSIDULID^ Agass. 

 NUCLEOLID^ Agass. 



Among the Cassidulidoe the primordial plates are actinal in Echinolampas, 

 (PI. 65, fig. ^), Fig. 155, Rhyn(!lio])ygus,2 and Neolampas (PL 04, fig. G) Fig. 

 156; they are only partly so in Echinoneus, where, perhaps owiug to the 

 obliquity of the test, the primordials ^^^ 



liave been pushed to one side in the 

 right anterior and the left posterior 

 interambulacrum. In Conolampas^ 

 (PI. 65, fig. 6'), the primordial plates 

 in the posterior lateral interambulacra, 

 Fig. 152, are excluded from the acti- 

 nal system by the intrusion in front of 

 them of the actinal plates of the late- 

 ral posterior ambulacra. These leave 

 visible but a small triangular slice of 

 the primordial plates in the angle of 



the adjoining ambulacral plates. The other interambulacral areas are also 

 much disturbed at the actinal system from the crowding of the prin:ordial 

 plates by the coronal plates, which tend to be resorbed and to pass into the 



^ Loven, Echiiioidees, p. 85. 



2 Loven, Etudes, Pis. VTT, fig. 67; XXIT, fig. 179. 



* In the list of known species of Kcliini given in the Report on the " Challenger'* Echinoidea 

 (p. 217), I retained the orighial name Conodyjms Sigsbei given to this remarkable Ca^ssiduloid in the 

 Preliminary Report of the " Blake " Echini (Bull. M. C. Z. V, No. 9, pp. 187, 190). In the Report on 

 the " Blake " Echini (Mem. M. C. Z. X, No. 1, p. 48) T suggested the name Conolampa-s for this spe- 

 cies, and gave my reasons for it. Loriol (Catal. Rais. des Echinod. de I'lsle Maurice. Mom. de la See. 

 de Phys. et d'Hist. Nat. de Geneve, XXVTII, No 8, p. 44, 18S:?) says that Conorli/pus Si(Js^•i is an 

 Echinolampas. Surely the details T have given in the " Blake" Report and the additional figures here 

 given do not warrant such an association, even though it may be difficult in the very youngest stages 

 to distinguish the young of Echinolampas and of Conolampas. 



30 nun. 



Fig. 152. Conolampas SiosnEi. 



