2G8 NOTES ON THE TERMIAN SYSTEM OF 



pact-limestone only; and, according to Baron Schanrotli, it is 

 fonnd in the eqnivalcnt deposit near Gera in Germany. 



2. A.? TUNSTALLENSIS, Kiiig. 



Six or seven specimens of a little subtriangular shell, which 

 Mr. Kirkby has recently taken, are referred to the ahove species, 

 as it is very probable that they belong to the species intended to 

 be described by Mr. King under that name. But only a refer- 

 ence to the type-specimen, of which it is to be hoped due care 

 has been taken, can substantiate this identification. For suppos- 

 tliem to be the same, the "diagnosis" in the "Perm. Monog." 

 is very incorrect, and the figure, pi. IG of that work, repre- 

 sents the shell as being almost flat. The specimens now before 

 me have a very swollen or tumid appearance, and are subtri- 

 angular in marginal outline. They are retained in the genus 

 Astarte with considerable doubt. 



In the shell-limestone, Tunstall Hill. 



23. MYOCONCHA, J. Sowerhy. 

 1. M. cosTATA, Broiun. 



I find nothing in the form of the teeth of this shell that re- 

 quires it to be removed from the genus Myoconclia. So far as I 

 have been able to ascertain, there is only one oblique cardinal 

 tooth in the right valve, which fits into a corresponding depres- 

 sion of the left. 



The examples from this district agree very accurately with the 

 original specimens described by Capt. Brown. In general, all 

 the specimens are strongly marked with several oblique radiating 

 ribs or planes over the posterior surface. Some specimens occur 

 at Byer's Quarry quite smooth, and more ovate than usual. 

 These have, I see, been prospectively named Pleuropliorus ovatus 

 in the " Perm. Mon." They do not appear to differ specifically 

 from the foregoing. 



It ranges through all the limestone series, but is most plentiful 

 in the shell-limestone of Tunstall and Humbleton, 



