1895.] Structure, Organisation, of Fossil Reptilia. 167 



If we take the differences between 1 and 4, 2 and 5, 3 and 6, we 

 get the following four sets of valnes for a, 6, c, and d. 





P. 







0. 



rence between 



a. 



I. 



c. 



d. 





212 



211 



210 



212 





. 211 



211 



212 



212 



3 and 6 



211 



212 



212 



212 





634 



634 



634 



636 





Mean = 



634-5. 







l = 6 ?i^ = 35-25, u = 1-733. 

 6X3 



From the resnlts given above it wonld appear that the index of re- 

 fraction of sulphnr is very near 1*73. 



The method adopted thns seems to be capable of giving accnrate 

 results ; no large quantity of material is required. The method is 

 also well snited for liqnids. 



The determination of the indices of other solids and liquids are in 

 progress. I shall give an account of these in a future commu- 

 nication. 



II. " Researches on the Structure, Organisation, and Classifica- 

 tion of the Fossil Reptilia. Part X. On the complete 

 Skeleton of an Anomodont Reptile (Aristodesmus Riitimeyeri, 

 Wiedersheim), from the Bunter Sandstone of Reihen, near 

 Basel, giving new Evidence of the Relation of the Anomo- 

 dontia to the Monotremata." By H. G. Seeley, F.R.S. 

 Received November 7, 1895. 



(Abstract.) 



"With the co-operation of the Trustees of the University Museum 

 of Basel and Professor Riitimeyer, the author has examined the 

 fossil described by Dr. Robert Wiedersheim in 1878 as Labyrintho- 

 don Rutimeyeri. The bones are differently interpreted : — 



The reputed humerus is the interclavicle. 

 The reputed scapula is the humerus. 

 The reputed supra-scapula is the left coracoid. 

 The reputed supra-scapula is the right scapula. 

 The reputed right and left coracoids are the pre-coracoid and cora- 

 coid of the right side. 

 The reputed clavicles are the ribs. 



Five digits are identified in place of four in 1878. 



