from Southern JSitjerid. 195 



wliicli by seveiiil inlets is in communication with the sea, it 

 is considered that the deposits contaiiiin<>- the shells would 

 represent an old lagoon area which probably formed a con- 

 tinuation of that already existing. The specimens seem to 

 exhibit a Mediterranean or Atlantic facies, and although it 

 has been necessary to introduce a few new specific names, 

 nearly all show certain phases of modern character. Some 

 of the known species referred to range from Upper Tertiary 

 times in Europe and England, such as the Pliocene, so that 

 it is possible the deposits may belong to either an ancient 

 part of the post-Pliocene period or to even the Pliocene itself ; 

 in any case they are not supposed to be of older date than 

 Pliocene. More perfect material is, however, wanted before 

 a truly accurate determination of the horizon is really 

 j)0ssible. 



The writer wishes to acknowledge valuable assistance in 

 the drawing up of this paper from his colleague at the British 

 Museum (Natural History), Mr. Edgar A. Smith, I.S.O., who 

 is in agreement with him in recognizing the fauna assugo-es- 

 tive of the modern Atlantic or Mediterranean facies. 



PeLECYPO DA. 

 Fleria sp. (Pl. VI. fig. 1.) 



Description. — Shell obliquely oblong, compressed, fragile, 

 nacreous, smooth, obsoletely striated; umbo very anterior, 

 nearly marginal ; cardinal line short, without terminal exten- 

 sions, furnished below with an oblique groove directed 

 posteriorly. 



Dimensions (largest valvf). — Length = 17, height = 32 mm. 



Remarks. — Two examples represent this form, consisting 

 of right valves of diflfeient sizes. The smaller shows some 

 obscure radial striations on the surface. 



There are no aliform expansions to either specimen, the 

 cardinal line being short and only equal in extent to the 

 length of the shell. The specimens are mere films on the 

 sandy matrix, and although the valves are much compressed 

 the larger one possesses a very slight oblique axial con- 

 vexity, as well as a rather feeble depression postero-dorsally. 



If we regard these remains as very decorticated, and in 

 that manner account for the absence of the usually produced 

 cardinal extremities, then it is possible that they belonged to 

 Lamarck's Avicala tarentiua (^ = Mytilas hirundoj Linnaeus, 

 pars), an Atlantic species, varieties of which also occur in 

 the British and Italian Pliocene beds. The margins are 



13* 



