ORTMANN : TERTIARY INVERTEBRATES. 55 



Fam. CLYPEASTRIDsE Ag. 



Gen. SCUTELLA Lmck. 

 4. SCUTELLA PATAGONENSIS Desor. 



PI. XI, Fig. 4"-'. 



1846 Scutella patagonensis Desor, in : Bull. Soc. geol. France, ser. 2,v. 4, 287. 



1846 Echinamchnius juliensis Desor, ibid. 



1847 Scut. pat. and Ech. jul. Agassiz and Desor, in: Ann. Sci. nat. ser. 

 3, v. 6, p. 135 and 134. 



1858 Scut. pat. and Ech. jul. Desor, Synops. Ech. foss., p. 234 and 231. 



1897 Scut. pat. and Ech. jul. v. Ihering, in: Rev. Mus. Paul., v. 2, p. 337 

 and 336. 



1898 Iheringia patagonensis Lahille, in: Rev. Mus. La Plata, v. 8, p. 437, 

 pi. i and 2. 



Test depressed, margin thin. Outline circular, oval, subpentagonal, or 

 more or less transversely dilated (alate), sometimes almost semi-circular, 

 with the posterior margin truncated. Margins often undulated and the 

 posterior one with a more or less distinct median incision. Apex sub- 

 central. Ambulacral petals of uniform size, lanceolate, more or less open, 

 sometimes lyrate, with a few scattered pores diverging from the extrem- 

 ity of the petals. Interambulacral plates of upper side increasing in width 

 from the apical system to near the end of the petals ; then they decrease 

 suddenly in width, so that the interambulacral space narrows considerably 

 toward the periphery. On the periphery the interambulacral space is con- 

 siderably less broad than the ambulacral space. Ambulacral furrows of 

 lower side dividing into two branches at a short distance from the mouth, 

 each branch subdividing again near the periphery of the test into 2 to 4 

 branchlets. Anus submarginal, distant from the posterior edge of the test 

 about i2 times its diameter (in young individuals it is marginal, with a 

 slight inclination toward the lower surface). 



Diameter of largest complete individual of rounded form : 62 mm; of 

 a fragment : 70 mm ; alate form : longitudinal diameter : 76, transverse 

 diameter, 94 mm. 



Remarks: The two forms of Scutellids, described as two different spe- 

 cies belonging to the genera Echinarachnius and Sctdella respectively, 



