CASS1DULID.E. 



117 



they are examined on the abactinal side (PI. 52, fig. 1). The intrusion or 

 flow of the anal plates into the interambnlacral system of the Echinothuriae 

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

 Mortensen, yet Loven 1 has suggested something of the same kind as possible 

 when comparing a Collyrites to a Culcita-like starfish. 



5 mi 



PETALOSTTCHA Haeckel. 



CASSIDULID^J Agass. 

 NUCLEOLID-S! Agass. 



Among the Cassidulidse the primordial plates are actinal in Echinolampas, 

 (PI. 65, fig. 2), Fig. 155, Rhynchopygus, 2 and Neolampas (PI. 64, fig. ti) Fig. 

 156 ; they an' only partly so in Eehinoneus, where, perhaps owing to the 

 obliquity of the test, the primordials 

 have 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 interarribulacra, 

 Fitr. 152, arc 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 interambnlacral areas are also 

 much disturbed at tire actinal system from the crowding of the primordial 

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



1 Loven, Echino'idees, p. 85. 



- Loven. Etudes, Pis. VII, fig. 07: XXII. n>. 170. 



3 In the list of known species of Echini given in the Report on the " Challenger'' Echinoidea 

 (p 217), I retained the original nam.' Conoclypus Sigsbei given to this remarkable Cassiduloid in the 

 Preliminary Report of the •• Blake" Echini (Bull. M. C. Z. V, No. 0, pp. 187, 190). In the Report on 

 the " Blake " Echini (Mem. M. C. Z. X, No. 1, p. IS) I suggested the name Conolampas for this spe- 

 cies, and gave my reasons for it. Loriol (Catal. Rais. des Eehinod. de l'Isle Maurice. Mem. de la Soc. 

 de Phys. et d'Hist. Nat. de Geneve, XXVITI, No 8, p. 41, 1883) says that Conoclypus Sigsbei is an 

 Echinolampas. Surely the details I 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 SiosrsEr. 



