GEIiTBRA AND aROTJPS OF THE ECHINOIDEA. 25J 



large; posterior pair longest, curved, with tlie concavity out- 

 vrards, unclosed distally; all in the depressions of the test, 

 forming an acute angle at the apex. 



Peristome excentric in front, subcircular. Periproct elliptical, 

 posterior. Pascioles : a peripetalous and a subanal. 



Fossil. Eocene: Europe, Asia, Sind ; and Java (Tertiary). 



Dames drew a distinct peripetalous fasciole ; and in Duncan 

 andSladen's specimens there is every indication of a subanal. 



In the species described by Dames there are some primary 

 tubercles scattered in the lateral interradia. 



The genus should come near Brissopsis. 



Grenus Spatangtis, Klein, 1734, Nat. Bisp. Ech. p. 33. Lamarck, 



1801, Syst. Anim. s. Vert. p. 348. Gratj, 1825, Ann. PMl. 



vol. X. p. 8 ; 1855, Cat. Bee. Bch. Brit. Mus. pt. i. p. 46. 



Besor, 1858, Synopsis, p. 419. A. Agassiz, 1872-74, Bevi- 



sion, pp. 158, 564, Loven, 1874, Etudes, pis. 208-212. 



Test thin, large, cordiform iu marginal outline, broad, rounded 



and grooved anteriorly, truncated at the narrower and oblique 



posterior surface, dorsally slanting upwards and backwards, 



depressed, never as high as broad. 



Apical system small, slightly excentric in front and in front 

 of the vertex ; four basal plates perforated ; and the madreporite 

 extending between the postero- lateral basal plates and between 

 the posterior radial plates into the interradium. Anterior ambu- 

 lacrum in the broad deep groove ; pairs of small pores distant. 

 Antero-lateral ambulacra with the petaloid parts broad, long, diver- 

 gent ; the interporiferous areas tumid and flush ; the poriferous 

 zones broad, sunken ; the pores small in the anterior zone near 

 the apex, large where the zones are large, closing at an angle dis- 

 tally; anterior poriferous zone may be ill-developed. Postero-lateral 

 ambulacra broad, petaloid, closed, subequal to the antero-lateral, 

 and. with large flush interporiferous areas and sunken poriferous 

 zones. Actinally the ambulacra form most of the peristomial 

 margin anteriorly and at the sides ; and the postero-lateral 

 ambulacra are well developed, the 6-8 plates of the inner 

 zones being within the subanal fasciole, and two with large 

 perforations. 



Peristome excentric in front, with a projecting labrum ; an 

 amphisternum. Periproct large, supramarginal, elliptical, trans- 



