256 PEOF. p. M. dttncan's revision of the 



of Spatangus. A lateral fasciole at the height above the margin 

 of the test, corresponding to the ends of the ambulacral petals, 

 passing above the anus. A subanal fasciole. 



Fossil. Eocene : Europe ; Africa ; "W. Indies ; Asia. 



Beceiit. Caribbean Sea. 



Sfomaporus, Cotteau, 1888, Compt. Eend. vol. cvii., differs be- 

 cause it has a sharp edge and an almost central peristome, but 

 it can hardly be otherwise than one of this group. 



G-enus NACOSPATAwaus, A. Agassiz, 1873 (subgenus), Bull. Mus. 

 Oomp. Zool. vol. iii. p. 189 ; 1874, Zool. 'ILassler ' Exped., 

 Gat. Mus. Oomp. Zool. Rarv. No. viii. 1. Ecliini, p. 17. 



Test small, thin, ovoid in tumid marginal outline, arching 

 regularly dorsally to the vertex, which is between the apical 

 system and the nearly vertical posterior truncation, broadest in 

 front of tlie centre, narrow behind, without an anterior groove. 



Apical system slightly exceutric in front, small, with three per- 

 forated basal plates, and the madreporite in the right anterior, 

 which is imperforate. 



Anterior ambulacrum different from the others, the interpo- 

 riferous area covered with small secondaries and miliaries ; pores 

 small. Antero-lateral ambulacra flush, with slightly sunken pori- 

 ferous zones ; the anterior poriferous zone with single pores, the 

 posterior with large pairs of pores which become single aetinally. 

 The postero-lateral ambulacra with broad poriferous zones and a 

 narrow interporiferous area, petaloid and nearly closing. 



Peristome large, excentric in front, semilunar, plated, with a 

 broadly projecting labrum. The sternum narrow, keeled, tuber- 

 culate, flanked by broad ambulacral areas. Periproct posterior, 

 transversely elliptical, with two concentric rows of anal plates, 

 below it a subanal plastron with a fasciole, and a beak at the 

 lower end of this plastron which is continuous with the actinal 

 surface. Some anal branches of the subanal fasciole. Spines 

 longest aetinally, short and curved at the base. 



Recent. Juan Fernandez, 65 fathoms. 



The generic characters of Gualtieria, Desor, have necessarily 

 been enlarged by the discovery by M. Cotteau of a subanal 

 fasciole in the typical species from Saint Palais. 



