46 MR. F. J. BELL ON A NEW GENUS OF ECHINOIDS. [Feb. 3, 



specimen the difference between the outer and inner pore can still 

 be observed, just as well as in the upper portion of the rows. 

 What, however, is more remarkable now remains to be noted : 

 the outer row of pores may be traced from the point where they 

 cease to be accompanied by the inner row as far as the actinal 

 region, and that with complete regularity of spacing, and in lines 

 which only here and there diverge from being completely straight ; 

 when they reach the phyllode they of course exhibit some modi- 

 cation ; but that is of no importance for the moment. What we 

 have here is the regular repartition of one row of pores from the 

 apical to the oral pole. In this, as in several other points, the 

 specimen under description approaches the genus Conoclypeus, the 

 existence of which in the present epoch has been lately signalized 

 by Prof. Alex. Agassiz* : in Conoclypeus sigsbei the paired arrange- 

 ment of the ambulacral pores does not extend over more than two 

 thirds of the abactinal surface, while C. anachoreta, Agassiz (L.), 

 is seen to retain the paired arrangement from the apical to the oral 

 area (see Desor, Echinides fossiles, pi. xxxiii. figs. 5-7). 



We may find, then: the following series: — 



Conoclypeus anachoreta : pores in pairs extend over the whole of 

 the ambulacral area. 



PalcBolampas, nov. gen, : pores in pairs extend to the ambitus ; 

 outer row extend to the peristome regularly. 



Cvnoclypeits sigsbei : pores in pairs extend over part only of the 

 abactinal area ; outer rows as in FalcEolampas. 



Echinolampas : pores of corresponding paired rows unequal. 



E. depressa: pores of outer rows extend regularly to actino- 

 stome. 



E. oviformis : pores of outer row not regularly distributed on the 

 plates between ambitus and actinostome. 



Neolampas : pores in single row (paired arrangement altogether 

 lost). 



AVhether the mass of their characters is not such as to justify the 

 union of 0. anachoreta and C. sigsbei in a single genus, and the 

 generic separation of the new form (Palceolampos), is a point which 

 I will discuss later on. The table as here arranged, seems to throw 

 discredit on the union of Echinolampas depressa and E. oviformis in 

 the same genus ; but there are other points of importance in the 

 structure of the Echinoderm than the characters of the ambulacral 

 system, and these must have their due weight. 



The bourrelets of the actinal system are distinct, but they do not 

 project into the buccal cavity ; they are well rounded, not pointed at 

 all, and may be said to be due rather to ihe development of the 

 phyllodes, which mark off the interambulacral periphery of the 

 actinostome, than to any modification in the interambulacral plates 

 themselves ; judging from the photograph of C. sigsbei, they are 

 less developed than in that new form, while they have no such 

 sharp projection as in Echinolampas oviformis ; the outer row of pores 

 bends slightly outwards, and then inwards so as to approach its fellow; 

 ' Bull. Mue. Comp. Zoology, t. no, 9, p. 190. 



