146 



THE LIAS AMMONITES. 



Gasteropoda. 



Pleurotomaria subdecorata, (VOrh. 

 Chemnitzia lineata, Sow. 

 *Turbo capitaneus, M'unst. 



Trochus duplicatus, 8ow. 

 *Natica adducta, Fhil. 

 — Oppelensis, Lye. 



Lamellibranchiata. 



*Lima bellula, var., Lye. ^ Mor. 

 *Modiola plicata, Sow. 

 *Perna rugosa, Milnst. 

 *Hinnites abjectus, Phil. 

 *Pecten articulatus, Goldf. 

 *Gresslya abducta, Phil. 



* — conformis, Agass. 

 Myacites arenacea, Lye. 



*Homomya crassiuscula, Lye. 



Goniomya angulifera. Sow. 

 *Myoconcha crassa, Sow. 

 *Cypricardia cordiformis, Desh. 

 *Pecten comatus, Milnst. 



Opis carinatus, Wright. 



* — lunulatus, Sow. 

 Cypricardia brevis, Wright. 

 Cardium HuUii, Wright. 



— Oppelii, Wright. 

 Cucullsea ferruginea, Lye. 



Terebratula subpunctata, Dav. 

 — trilineata, Young. 



Cucullsea olivseformis, Lye. 

 *Lima electra, d'Orh. 

 Unicardium, nov. sp. 

 Tancredia, nov. sp. 

 Trigonia Ramsayii, Wright. 



* — striata, Sow. 



* — costata, Sow. 

 Pecten textorius, Goldf. 



*Plioladomya fidicula, Sow. 

 — arenacea, Lye. 



Lima ornata. Lye. MS., nov. sp. 

 Astarte lurida, Sow. 



* — excavata, Sow. 



— detrita, Goldf. 



— complanata, Roemer. 



— rugulosa, Lye. 

 Gervillia fornicata, Lye., MS. 



* — Hartmanni, Goldf. 

 Nucula Jurensis, Quenst. 



Brachiopoda. 



Rhynchonella cynocephala, Rich. 

 — Jurensis, Quenst. 



In the above list the species marked with an asterisk are found hkewise in the 

 Inferior Oolite ; but the specimens from the sands are nearly all dwarfed forms, showing 

 that the physical conditions under which they lived were unfavorable to their development. 

 The stunted growth of the stationary Lamellibranchs forms a striking contrast to the 

 size, number, and variety of the locomotive Cepljalopods interred with them in the same 

 bed ; the dawning existence of the former appears to have been a struggle for life, whilst 

 the conditions under which the Cephalopods existed were favorable to their continuance 

 in time, as shown by the number of species and individuals found in the Frocester beds ; 

 their life, however, was abruptly brought to a termination by some great physical change 

 which took place about the commencement of the deposition of the Oolitic formations. 



Foreign correlations. — The Jurensis-mergel was first j)ointcd out by Professor 

 Quenstedt ^ as the uppermost member of the " Shwarzer Jura," its importance in 

 ^ ' Flozgebirge Wiirtembergs,' pp. 2G7 and 539, 1843. 



