240 PEOF. p. M. Duncan's eevision of the 



Genus Maretia. 



Eupatagus. 

 Subgenus Macropneustes. 

 Genus Nacospatangus. 



Gualtieria. 



Linopneustes. 



Neopneustes. 



Cionobrissus, 



Echinocardium, 



Breynia. 



Lovenia. 



G-enus Micra.stbe, Agassiz, 1840, Gat. Si/st. p. 2 ; 1847, Gat. 

 Eais., Ann. d. Sci. Wat. ser. 3, vol. viii. p. 23. Desor, Synopsis, 

 1858, p. 360. Loven, 1874, Etudes, pis. xi., xxxiii. Duncan 

 Sf Sladen, 1884, Foss. EcJi. W. Sind, pt. iii. p. 189, pi. 

 xxxvii. (Pal. Ind. ser. xiv.). Gauthier, 1887, Bull. Soc. d. 

 Sci. Hist, et Nat. de V Tonne, vol. 41 e (pub. 1888), p. 367. 

 Test moderate or large, cordiform, narrowest and truncated 

 posteriorly, tumid, rather depressed. 



Apical system excentric in front, small, witli four perforated 

 basal plates, rarely witb only tbree perforations ; the madreporite 

 either restricted to the right anterior basal, or passing beyond 

 it and separating the postero-lateral basal plates. (The Tertiary 

 species have only three genital perforations.) 



Ambulacra diverse, sunken ; the anterior apetaloid, with the 

 small pairs of pores becoming distant towards the ambitus ; the 

 antero-lateral ambulacra subpetaloid dorsally, diverging, longer 

 in the subpetaloid part than the postero-lateral ; postero-lateral 

 ambulacra forming a slight angle at the apex ; pores of both areas 

 elongate. 



Interradia with large plates ; actinally the right postero-lateral 

 area has the second and third plates of zone a coalesced, the cor- 

 responding plates of the left postero-lateral (4) interradium being 

 separate. A symmetrical amphisternum, but without an epi- 

 sternum ; many plates between the sternum and the periproct, 

 which is oval and high up in the truncated or grooved j)osterior 

 face, and sometimes overhung by the end of the keel of the 

 posterior interradium. Subanal fasciole broad ; the sixth ambu- 

 lacral plate and four others being altered in shape, and each 

 having a pair of pores within the fasciole. 



