BY JAMES C. COX, M.D., F.L.S., ETC. 277 



Cretaceous and Wealden formations ; three in the Jurassic ; one, 

 Edlieria minuta, with its varieties in the Ehcetic stages, and the 

 same species also in the Trias formations ; three in the Permian, 

 two in the Carboniferous, and one in the old Bed Sandstone. We 

 shall now have to add another to the Trias stages as found in 

 New South Wales. 



On the authority of Professor M'Coy and of the late Eev. W. 

 B. Clarke, Eupert Jones states that ''the Jurassic-like flora of 

 Australia, and of Southern Africa, have been hitherto collected 

 without affording any clear traces of the Estheria. In 1862 there 

 were about twenty-two species of living Estheria recorded, and 

 some of them were from Australia ; and I believe there are still 

 others to be described from Australia, or else the same species 

 exist here as are found in other parts of the world. " Eecent 

 Estherice, says the same authority, are found in fresh, rarely 

 in brackish water." Gruided by this fact, and taking for granted 

 that our fossils were true Estherioe, and that Estlierim have always 

 had fresh-water habitats, we should suppose that the deposits in 

 which they are found free from any appearance of having been 

 drifted, must have been formed in rivers, lakes, or lagoons ; but 

 they are occasionally found to occur with marine shells, although 

 they are sometimes found in strata destitute of marine fauna." 

 Jones accounts for their association with marine evidences as 

 being the result of '' driftage, or of very rapid changes of condition 

 such as might be brought about by the alternate occupation of a 

 lagoon by sea and river water. Seeing too that the recent 

 EsthericG appear as it were suddenly (like the apus) in j)Ools and 

 ditches of rain water, and are quickly developed in tanks and 

 ponds that are dry for even ten or eleven months in the year, it 

 is not unlikely that pools of fresh water temporarily formed on a 

 flat seashore may have been inhabited by EstJierm destined to be 

 quickly buried in the first wind-drift of sand, or at the return of 

 high tides." The only part of these little shell insects, as they 

 are designated by Latrelle, which are preserved in a fossil state, 



