152 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



Shape. — IMedium size, up to 50 mm. long, oval with smoothly 

 rounded marginal outline, steep sides, slightly flattened adapical sur- 

 face, with greatest width and height posterior to center. 



Apical system. — Anterior, monobasal, large central area perforated 

 with madreporic pores, oculars small. 



Ambulacra. — Petals open, short, extending between one-half and 

 two-thirds distance to margin; petal III longer than paired petals; 

 interporiferous zones slightly narrower than poriferous zones; pores 

 strongly conjugate, outer pore very elongate transversely, inner pore 

 slightly elongated. All petals flush with test. Suture between am- 

 bulacra plates passing through pores. Poriferous zones of same petal 

 of equal length. 



Adoral intcravibulacra. — Single large plate in each interambula- 

 crum at peristome, preceded by pairs of slightly alternating plates of 

 nearly equal size. 



Periproct. — Supramarginal, midway between apical system and 

 margin, opening very narrow, longitudinal, in a long narrow groove 

 extending to posterior margin. 



Peristome. — Anterior, pentagonal, width equaling height. 



Floscelle. — Bourrelets very prominent, sharply inflated, toothlike. 

 Phyllodes depressed, widened, single pored, very few pores, four in 

 each outer series, only one occluded pore in each phyllode, occurring 

 in right half-area in ambulacrum III, anterior in ambulacrum II 

 and IV, and posterior in I and V ; buccal pores present. 



Tiiherculation. — Tubercles much larger adorally, with bosses ec- 

 centric anteriorly in large, deep scrobicules ; naked area in inter- 

 ambulacrum 5, ambulacrum III. 



Occurrence. — Upper Eocene of Australia. 



Location of type specimen. — British Aluseum (Natural History). 



Family ARCHIACIDAE Cotteau and Triger, 1869 



Medium size, elongate, highly inflated; apical system tetrabasal, 

 very anterior, four genital pores ; periproct inframarginal, longi- 

 tudinal ; peristome very eccentric anteriorly, longitudinal ; petals 

 broad, closing distally, petal III absent or very short, with doubling 

 of pores ; single or double pores in ambulacral plates beyond petals ; 

 bourrelets moderately developed ; phyllodes slightly widened, double 

 or single pored, two series of pores in each half -ambulacrum, with 

 or without buccal pores; tubercles slightly larger adorally, narrow, 

 naked zone in interambulacrum 5. 



