189 



investigation to which the Cotteswold Club may advantageously 

 apply itself. As we have already seen in the case of the junction- 

 beds between the Lias and the Inferior Oolite, so we see here 

 exemplified, those mixed characters partaking of the features of 

 two contiguous formations, which renders it very difficult to draw 

 a line of demarcation, and to assign to each its exact share in 

 the beds in question. Looking merely to mineralogical character, 

 a casual observer would at once place his finger on the well- 

 marked line of junction, where the " Red Marl 1 ' is opposed in 

 strong contrast to the dark overlying clays in contact with it, 

 nnd would, without hesitation, allot the one to the Trias, and the 

 other to the Lias. But an examination of the fossil contents of 

 the beds, as enumerated above, will lead to a very different 

 conclusion. 



The Bone-bed, which occurs about the middle of the series, 

 is charged with vertebrate remains of a decidedly Triassic 

 character ; though in many localities the vertebrate remains of 

 the bone-bed continue upwards in part into Ihe blue stone of 

 Ammonites planorbis above, and are even found in a separate liassic 

 bed. Fossil remains of a similar type are met with at Westbury in 

 the lowest baud of the dark clay in immediate contact with the 

 " Red Marl," and they are traceable upwards in the beds num- 

 bered 2 and 7 respectively. With No. 7, which immediately 

 overlies the Bone-bed, we lose all further traces in this Section 

 of these peculiar records of vertebrate existence, and after the 

 interposition of eight feet of clay, the lighter colour of which 

 may perhaps vindicate a miueralogical change in the circum- 

 stances of its deposition, we arrive at a very remarkable band 

 which is characterised by the presence of Estheria, and from that 

 circumstance is designated the Estheria-bed. This fossil, which 

 was formerly considered to be a bivalve Mollusk, and as such 

 received the appellation of Posidonia minuta, is now transferred 

 to the Entomostraca, though with some doubts as to whether it 

 be correctly referred to that Order of Crustaceans. Should such 

 be the case, it may possibly suggest for it a freshwater habitat, a 

 circumstance in some degree supported by the discovery by Mr. 

 Brodie of Cypris, plants, and Cyclas in the limestone-band No. 

 13 which overlies it. 



Tn the Journal of the Geological Society for November, 1856, 

 Mr. Rupert Jones writing upon Estheria minula, observes that, 

 " Although the recent Estheria is a Marine Crustacean, yet since 

 very closely allied forms are of fresh water habits, and since among 

 bivalved Entomostracans, different species of a genus, and even 

 the individuals of a species, occasionally live either in marine or 

 in fresh water, there is no certain evidence afforded by the fossil 

 in question whether the so-called Triassic deposits in which it 

 is found were formed in rivers, lakes, or seas." According to 

 Mr. R. Jones different species of Estheria are met with in 



VOL. II. T 



