294 



ECHINODERMATA— ECHINOZOA 



PHYLUM IV 



shaped, broad. Periproct supramarginal. Upper Cretaceous. H. radiatus 

 (Lam.). 



Cardiaster Forbes. Similar to Holasfer, but anterior groove deeper and 

 with angular margin. Periproct oval, placed in a depression in the truncated 

 posterior face. A more or less complete marginal fasciole passing below the 

 periproct. Cretaceous. 



Subgenus Infulasfer Hagw. Test higli in front, narrow ; anterior groove deep and with 

 strong lateral keels. Fasciole absent. Upper Cretaceous. 



Urechinus and Cystechinus A. Agassiz. Late Tertiary and Recent. Calymne 

 Wyv. Thomson. Eecent. Enichaster de Loriol. Oligocene. All with uni- 

 porous Ami). 



Stenonia Desor. Like Ananchytes, except that the apical system is com- 

 pact, and the Amb equal. The solitary species, 'S. ttihercidcda (Defr.), is 

 abundant in the Upper Cretaceous (Scaglia) of the Southern Alps and the 

 Apennines. 



Family 5. Spatangidae Wright. 



Test ovoid or cordiform, longer than broad, with numerous plates, and usually 

 with an anterior groove. Ambulacra in a biviiim and trivium, the anterior differing 

 from the others in shape and construction. Pore-pairs of the petaloid parts differing 

 from the others. Fascioles present or absent. Cretaceous to Eecent. 



Section A. Adetes. All fascioles absent. 



Isaster Desor. Petals not closed. Peristome large, with a posterior 



labrum. Cretaceous, 



Eptiaster d'Orb. {Macraster Roemer). Anterior Amb in a groove ; paired 



Amb petaloid dorsally, with 

 elongate, unequal pores. lAmb 

 tumid dorsally. Peristome trans- 

 verse, tumid in front, and usu- 

 ally with a projecting labrum. 

 Periproct longitudinal, supra- 

 marginal. Cretaceous. 



Toxaster Ag. (EchinosjMtagus 

 Breyn.) (Fig. 416). Anterior 

 Amb in a broad shallow groove, 

 with unequal pore-pairs. Paired 

 Amb sub-petaloid, flexuous, with 

 unequal poriferous areas and 



unequal pore - pairs. Peristome transverse, sub - circular or pentagonal. 



Tubercles small, perforate and crenulate. Abundant in Lower and Middle 



Cretaceous. 



Ennalaster d'Orb. (Heteraster d'Orb.). Petaloid parts of antero-lateral Amb 



divei'gent, flexuous, tending to close, and with very unequal poriferous areas, 



of which the posterior are the largest ; pore-pairs oblique. Postero-lateral 



Amb short, divergent. Peristome labiate, wide, arched in front. Periproct 



in posterior truncation. Cretaceous. 



Hemipatagus Desor (Fig. 417). Test small, cordiform. Anterior Amb 



Toxaster complanatus Ag. 



Fl(i. 416. 

 Neocomian : 



Auxerre, Yonne. i/j 



