450 



PSEUDOLAMELLIBRANCHIATA 



duplicated, folded back, with pallial ocelli ; branchiae not con- 

 crescent with the mantle ; shell 

 with unequal " ears " at the mnl )0, 

 hinfje- teeth lamelliform, often ob- 



scure. Silurian . Principal 



genera : Pedum, Chlamys, Hinnites, 

 Heinifecten, A^yiussium, Pecten; Ari- 

 culopeden (Palaeozoic), Creni;pecten. 

 Fam. 5. Limidae. — Mantle edge 

 as in Pecten, tentaculate ; shell 

 sub-equivalve, eared, fixed by a 



byssus or free. Carboniferovis . 



Genera: Livia (Fig. 85, p. 179). 

 Liinea. 



Fam. 6. S})ondylidae. — Foot with 

 a peduncular appendage, no 



byssus, numerous pallial ocelli ; shell fixed by right valve, 



surface often very spinose, two cardinal teeth in each valve. 



Jurassic- •. Genera : Plicatula, SjJondylus ; Tcrquemia (Lias). 



Fig. 303.— Pecten 2jaUium L., East 

 Indies. 



Fig. 304. — Sjpondylus 

 petroselinum Sowb., 

 Mauritius ; on a coral. 



FA:sr. 7. Dimyidae. — Shell ostreiform, fixed, hinge with or 

 without symmetrical teeth, two muscular impressions. Single 

 genus, Dimya (Tertiary). 



