72 PROr. p. M. DUNCAN S EEVISION OP THE 



Cotteau, 1882, Bull. Soc. Geol, de Prance, ser. 3, vol. x.p. 34(5, 

 considers the genus to be close to Magnosia, and that there is a 

 species at Martigues ; but the structure of the apical system and 

 of th,e poriferous zones forms a decided distinction. 



III. Subfamily P e dini n ce (p. 59). 



Genus Pedina, Agassiz, 1840, Ech. Foss. de la Suisse, p. 33. 

 WrigJit, 1855, Pal. Soc, Ech. Ool. Form. p. 171. Duncan, 

 1885, Quart. Journ. Geol. Soc. vol. xli.p. 433. 



Test large and moderate, thin, circular or slightly pentangular 

 in tumid ambital outline, depressed. 



Apical system small, with nearly equal basal plates and small 

 excluded radial plates ; periproct moderate. 



Ambulacra narrow ; poriferous zones wide ; pairs of pores 

 in oblique triserial ranks, really in exceedingly arched triplets. 

 Plates low, crowded, and consisting of three components, each 

 with a pair of pores, the pair nearest the median ambulacral line 

 being in the adoral plate, which is either a long low primary plate 

 or a demi-plate, with its aboral suture convex towards the middle 

 component ; the middle plate of the three is the largest, is a pri- 

 mary, and its pair of pores is nearest the interradio-ambulaci'al 

 suture ; the aboral plate is either a low primary or a demi-plate, 

 and its adoral suture is convex towards the middle plate, its pair 

 of pores is further from the suture between the interradium and 

 ambulacrum than the pair of the middle plate. Tubercles in two 

 vertical rows ; and they are small perforate primaries. 



Interradia broad, and with two vertical rows of small primary 

 tubercles resembling those of the ambulacra, extending from 

 peristome to apex, and two or four rows of secondary tubercles, 

 which cease at or above the ambitus. 



Peristome small and with branchial incisions. 



Fossil. Oolite : England ; Europe. 



Subgenus Psetjdopedina (genus), Cotteau, 1858, Pev. et Mag. de 

 Zool. ser. 2, vol. x. p. 221; 1884, Pal. Frang., Jura, livr. 6(i, 

 p. 661, pi. 489. 

 Test subcircular in marginal outline, depressed or subhemi- 

 ppherieal. 



