BY R. ETHERIDGE, JUNE. 309 



third carina on each valve, iutermediate between the anterior and 

 posterior. It is much shorter than these, reaching across only 

 about one-third of the valves' width. It is obvious that the 

 Newcastle species could not be referred to L. klieveriana. 



Leaia Jonesi, mihi,* is another species from the Scotch Calcif erous 

 Sandstone Series, but here the diagonal carina is entirely absent 

 from both valves ; and it is thus equally obvious that no specific 

 relation can exist between it and L. Mitchelli. The valves of L. 

 Jonesi are thus divided into two very unequal portions. 



In the Coal Measures of Illinois, a peculiar species is met with, 

 named by Messrs. Meek and Worthen, L. tricarinata.j In general 

 outline it is not dissimilar to the Australian form, but like L. 

 klieveriana it possesses a third carina. This, however, is obliquely 

 placed immediately under the dorsal margin, and when the united 

 valves are viewed in apposition from above, the dorsal margin of 

 each valve is seen to be inflected " at right angles to the plane of 

 the valves, so as to form a distinct lanceolate corselet." Now, in 

 all the examples of L. Mitchelli I have seen, there is no trace of 

 this third keel. 



The remaining species of Leaia, L. loettinensis, Lespeyres, from 

 the Coal Measures of Wettin, and L. hcentschiana, Geinitz, from 

 the German Lower Permian, I am not able to refer to, from the 

 absence of the necessary literature, but full references will be 

 found to them in my previously quoted paper, J and the " Fifth 

 Report of the British Association Committee on the Fossil 

 Phyllopoda of the Palaeozoic Rocks. "§ 



It follows from this that we have in our Upper Coal Measures 

 a Leo.ia possessing all the general features of the genus, and most 

 nearly allied to L. Leidyi var. Salteriana, Jones. 



For the figures I am indebted to Mr. Charles Hedley, F.L.S. 



The following is the abbreviated diagnosis : — 



* Ann. Mag. Nat. Hist. 1879, iii. (-5), p. 257. 



t Illinois Geol. Survey Report, 1868, iii. p. 541, f. B 1-3, and ? C. 



t Ann. Mag. Nat. Hist. 1879, iii. (5), p. 262. 



§ Brit. Assoc. Report for 1887 [1888], p. 66. 



