92 PEOP. p. M. Duncan's revision of the 



and with only three pairs of pores in each compound ambulacral 

 plate. 



Fossil. Cretaceous : Europe. Eocene : Asia (Sind). 



The specific type is Gagaria {Micropsis) venustula, Dune & 

 Sladeu, 1884, Pal. Ind. ser. xiv., Foss. Ech. W. Sind, pt. iii. 

 p. 119, pi. xxii. figs. 1-7, from the Nummulitic. 



M. Lambert, 1888, Bull. Soc. d. Sci. Nat. de I'Tonne (extrait), 

 contains some excellent remarks bearing upon M . Pomel's sub- 

 division of Cyphosoona. 



VI. Eamily Arbaciid^, Gray. (Amended.*) 



Test moderate in size, subhemispherical or subcorneal, depressed 

 dorsally, flat actinally ; epistroma with granules, projecting 

 ridges, grooves, sessile glassy knobs, elongate or rugose, and 

 tall, especially on the bare dorsal interradial median areas. 



Apical system large ; the periproct oval and oblique ; the 

 periproctal plates four, rarely more, triangular ; the radial pores 

 adoral, double. 



Ambulacra straight, narrow, expanding near the peristome; 

 pairs of pores simple or in large arcs, or crowded actinally ; the 

 plates compound near the ambitus, the middle component a large 

 primary ; the adoral and aboral being demi-plates with very 

 curved sutures, their direction being nearly vertical towards the 

 ambulacral median line ; or the primary is adoral and the demi- 

 plates are aboral to it. 



Interradial plates with several or few vertical series of primary 

 imperforate, non-crenulated tubercles, usually larger than those 

 of the two rows of the ambulacra; with expanded bosses. Ten- 

 tacles heteropodous. Spheridia solitary or numerous. 



Peristome large, incurved at the sides of the ambulacra, and 

 with branchial tags. Teeth keeled. Jaws with the pyramidal 

 foramen open above. Plates united along the vertical sutures 

 by dowelliug, some of the projections may be large and lamellar. 



Genus Arbacia. 



Echinocidaris (gen. nov., non auct.). 



Ccelopleurus. 



Podocidaris. 



* For the structures noticed in this definition, see Duncan and Sladen, 

 Journ. Linn. Soc. yoI. xis. 1885, pp. 25 et seq. ; and Loyen, 1887, Ech. descr. by 

 Linuseus, pp. 80 et seq. 



