Mr. J. Lycctt on the Upper Lias of Gloucestershire. 159 



Cephalopoda. Gasteropoda. 



Ammonites bifrons, Brug. Pleurotomaria. 



- falcifer, Sow. Turbo capitaneui, Munst. 



< uiiiini ins. Sow. Conchifera. 



heterophyllus, Sow. Astarte lurida, Sou?. 



cornucopia;, Y. fy B. Lucina ? 



Jurensis, D'Orb. Tancredia laeviuscula, n. sp. 



Lythensis, Y. Of B. Posidonia Bronnii, Munst. 



crassus, Phil. Placunopsis sparsicostatus, n. sp. 



annulatus, Sow. Nucula Hausmanni, Horn. 



Ilrainstrensis, n. sp. Pecten. 



Belemnites compressus, Voltz. Gresslya gregaria, Rcem. sp. (G. An- 

 tripartitus. glica, Ag.) 



Nautilus latidorsatus, D'Orb. Lima gigantea, Sow. 



sinuatus, Sow. _ bellula, Mor. 8f Lye. 



Notes on the Testacea. 



Ammonites bifrons. A variety with compressed sides, in which 

 the falciform ribs are but little prominent. A few examples 

 occurred of the ultimate condition of growth, in which state it 

 may readily be mistaken for a distinct species, and probably 

 constitutes the A. Hildensis of Simpson. The costse have dis- 

 appeared upon the whole of the last volution, which presents 

 only densely arranged fine falciform lines which pass over the 

 back and the keel ; the lateral sulcation has become indistinct 

 through the flattening of the sides of the volution ; the back has 

 lost its rectangular figure and become rounded, sloping obliquely 

 upon each side from the keel, and the two dorsal grooves have 

 disappeared ; the keel itself has become more elevated and con- 

 spicuous. The inner or smooth portion of each volution over- 

 wraps and conceals the costated portion of the preceding volu- 

 tion, so that the entire aspect of the shell is smooth, and it is 

 only by breaking away a portion of the last volution near to the 

 suture that the ribs of the next volution can be exposed and 

 the identity of the species proved. It occurred abundantly. 



A. communis. Specimens were indifferently preserved, but 

 exhibited some of those varieties in the arrangement of the dor- 

 sal ribs, and in the general figure, which perplex collectors who 

 desire to separate them into the forms named A. communis, 

 A. Hollandrei, and A. Braunianus, a perplexity which is in no 

 degree lessened by the study of numerous specimens. Further 

 investigations into these forms are desirable. 



A. heterophyllus. Badly preserved examples, and few. 



A. cornucopia (A. fimbriatus, Sow.). A single fine example 

 in one of the higher beds. Some casts of young forms, appa- 

 rently of this species, have been prormrd in the lower zone of 

 the Cynocephala- stage at Nailsum-th. 



