42 W. KEEPING ON THE PIL^EOZOIC ECHINI. 



Prof. Duncan said that the analogies of the modern Echini with 

 the Palaeozoic are closer than is commonly imagined. The regular 

 Echini of modern times do not always preserve the same number of 

 plates in the ambulacral areas throughout. In modern forms the 

 ambulaeral pores run in straight series ; in the older ones they are 

 grouped obliquely. He remarked that some regular Echini have the 

 plates jammed up and broken near the buccal orifice, so that if found 

 separately their origin could not be determined. 



Mr. Keeping, in replying, stated that he had received great assist- 

 ance from the paper by Mr. E. Etheridge, jun., in the Quarterly 

 Journal. The fossil referred to as in the Jermyn-Street Museum 

 had the ambulacral and interambulacral plates very numerous ; no 

 such form had hitherto been recorded in Britain. He did not think 

 the modern flexible Echini were like the Palaeozoic. As to the 

 presence of crowded ambulacral plates in recent Echini, this was a 

 character which he thought did not affect the classification now 

 proposed. 



