﻿ADDENDA. 



191 



Stratigraphical positions and Localities. Numerous specimens more or less defective 

 in their general condition have been obtained by Mr. Meyer, in hard rock of the 

 Chloritic Marls in cliffs between Beer Head and Sidmouth, also from Pinhay Cliff near 

 Lyme Regis ; they present some variability in the prominence of the lines of growth, and 

 also in the costellae upon the area and escutcheon. Mr. Meyer states that specimens 

 occur of much larger dimensions in the cliffs near Dunscombe ; but from the hardness of 

 the rock he has found it impossible to get them out. 



Associated with them are the following species of Trigonia — T sulcataria, T. 

 jjennata, T. Met/eri, T. Vicargana, T. Archiaciana, T. scabricola ; and in the cliff a large 

 specimen has been seen of what Mr. Meyer believes to be T. quadrata, Ag., and also 

 indications of another large species. Ample and valuable imformation upon the position 

 of our species in connection with its localities and the associated Testacea will be found 

 in a paper by Mr. Meyer, ' Quart. Jour. Geol. Soc.,' August, 1874. The beds 10 to 12 

 of the classified section in the memoir contain one species, there assigned doubtfully to 

 T. crenitlata. 



The specimens from Pinhay Cliff are usually more rugose, their costae are more highly 

 ridged, their crenulations indistinct, the costse are of larger size and fewer in number, 

 probably it should be regarded as a variety, but their usual condition of preservation 

 forbids any rigid comparison. 



With the numerous Cretaceous Trigonia kindly forwarded to me by Mr. Cunnington, 

 were several examples from the Upper Greensand of Potterne, near Devizes, which 

 although partially deprived of the test retained some portions of their surface ornaments 

 upon the escutcheon and area, and should apparently be referred to the present species ; 

 they are now deposited in the Museum of the Royal School of Mines. 



T. crenulata, Lam., has also been recorded by Professor R. Tate, in the Hibernian 

 Greensand of the North East of Ireland, 'Jour. Geol. Soc.,' 1804, p. 30. As the 

 position accords with that of our species, it is not improbable that both of them 

 represent the same Trigonia. 



