48 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



SO far as one can bo told, do not differ, except in size, from the 

 smaller ones. 



It can not be definitely stated that the Hatter and nearly smooth 

 shell here described as the right valve of the species reallj'^ had that 

 relation. The correspondence in size and shape, however, and occur- 

 rence in the same beds render this interpretation quite probable. If 

 so, however, it is certain that the form under consideration is not 

 an Aviculipecten^ since a l)yssal sinus, which is well developed in that 

 genus, is here inconspicuous or absent. 



In shape and sculpture this form recalls to a certain extent some of 

 the liussian species of Avlcula. x\. hazajiensis De Verneuil, of the 

 Russian Permian, is perhaps the nearest of these, though it is still con- 

 siderably different. Avicula elegcmttda Stuckenburg, of the Gschelian, 

 is still more different. 



Locality and horhon. — Post-Penns^'lvanian (!!) (Kui-chou series); 

 near Ta-ning-hien, East Ssi-ch'uan (Station 5). 



