THE YORKSHIRE COAST. 



171 



Naiadfc. Unio ? 1, Listeri, 2, concinnus, 3, crassiusculus, lias; 4, peregri- 



nus,* cornbrash ; 5, abductus, Inferior oolite and marlstone. 



Mytilaceac. Modiola, 1, scalprum, marlstone ; 2, plicata, inferior oolite ; 3, bi- 



partita, calcareous grit; 4, cuneata? Oxford clay, Kelloieays 

 rock, and cornbrash ; 5, imbricata, Bath oolite; 6, Hillana, lias; 

 7, ungulata,* coralline, Rath, and inferior oolite ; 8, pulchra,* 

 JfCellotcays rock ; 9, aspera ? inferior oolite ; 10, inclusa,* coral- 

 line oolite. 



Mytilus, 1 , cuneatus,* inferior oolite. 

 Hippopodium ponderosum, coralline oolite and lias. 



Arcadae. 



Trigoniaceae. 



Division 1. Sub-division 2, mantle entirely open. 



Cuculljea, 1, oblonga, 2, contracta,* 3, triangularis,* 4, pectinata,* 

 coralline oolite ; 5, elongata, coralline, Bath, and inferior oolite ; 

 6, concinna,* Oxford clay and Kelloways rock ; *J, imperialis,* 

 8, cylindrica,* Bath oolite ; 9, cancellata,* Bath and inferior 

 oolite ; 10, reticulata,* inferior oolite ; 11, Speeton clay ; 12, lias. 



Area, 1, quadrisulcata, 2, aemula,* coralline oolite. 



Nucula, 1, ovata, 2, subrecurva,* Speeton clay ; 3, subrecurva? in- 

 ferior oolite ; 4, coralline oolite ; 5, elliptica,* 6, nuda, 'J, Ox- 

 ford clay ; 8, variabilis, 9, lachryma, Bath and inferior oolite ; 

 10, axiniformis,* inferior oolite; 11, ovum, 12, complanata,* 

 upper lias. 



Trigonia, 1, costata, 2, clavellata, coralline oolite, fyc. ; 3, conjun- 

 gens,* Brandsby slate ; 4, striata, inferior oolite ; 5, literata, lias ; 

 6, angulata, inferior oolite. 



Division 2, with a large nearly central muscle, for closing- the valves. 



Pinnaceae. Pinna, 1 , gracilis,* Speeton clay ; 2, mitis,* Oxford clay and 



ways rock ; 3, lanceolata, coralline oolite and calcareous grit ; 

 4, cuneata,* cornbrash and Bath oolite ; 5, folium, lias. 

 Trigonellites, 1, antiquatus,* coralline oolite; 2, politus, Oxford 



clay. 

 Oxygonse. Perna quadrata, coralline and Bath oolite. 



Crenatula ventricosa, lias. , . 



Inoceramus, 1, Cuvieri, 2, Brongniarti, 3, mytilloides, chalk; 

 4, dubius, lias. 



z 2 



