78 FOSSIL ECHINI FRO.Nr Till-: TERTIARY 



smallest width ou the posterior border z^ 20 mra. 

 height = 4 mm. 



6. Peronella decagonalis Ag. is indoubtedly iden- 

 tical with Scutella decagona Jlerkl. (1. c. pag. 9 . tab. I , 

 fig 6). The individual figured by Her klots appears to be 

 distinguished from this recent species by the lesser eleva- 

 tion of the middle part of the superior surface ; however 

 another somewhat smaller specimen , measuring 33 mm. 

 entirely corresponds to the typical P. decagonalis even in 

 this respect , and so this deviation must be regarded as no 

 more than a variety. The lanceolate shape of the petals, 

 is indeed different from the straightbordered petals of 

 the large individuals of P. decagonalis ; this however is a 

 consequence of the different age of the specimens. 



I can no more separate L. angulosum Herkl. (1. c. pag. 

 8 , tab. 2 , fig. 4) from P. decagonalis and likewise I 

 take L. rotundum Herkl. to be the same species , as far as 

 least as the bad cond,ition of this la§t yarned fossil permits 

 to judge. 



L. tenuatum Herkl. (1. c. pag. 9, tab. I, fig. 7) is per- 

 haps distinct from the above mentioned forms by its con- 

 cave inferior surface. Only it is too insufficiently preser- 

 ved to allow of a definite judgment. 



7. J*ei*o»»cll« orhicwluris A.g., rn Laganum orhicu- 

 lare Ag. (Herkl. 1. c. pag. 7, tab. 2, fig. 3) , was rightly recog- 

 nized by Herklots , as far as I can see ; however Agas- 

 siz puts forward the possibility of this species being 

 the young stage of P. decagonalis Ag. (Revision of the 

 Echini Part. Ill, pag. 521). I believe this to be highly 

 probable , especially on comparison of the young specimen , 

 named by Herklots L. angulosum., with L. orhicidare. It 

 is only the shape of the border , by which in this case 

 a distinction might be effectuated , and as the differei>,t 

 La^rt/ïum-species vary so considerably in this respect, it 

 may not serve to distinguish species. Nevertheless I make 

 separate mention of P. orbicularis and P. decagonalis be- 

 cause the superior surface of the fossil P. orbicularis is 



^otos from the Leydeu TVIuseum . "Vol. II. 



