320 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxv. 



itv of their valves. Hence, he had had no opportunity to observe the 

 principal evidence in the case, namely, the transition from K. penn- 

 sylvanica to K. clarkei, and the fact that while the valves of Bollia 

 are equal, those of Klmdenella are unequal. In passing, it may be 

 said that Bollia is regarded as an early derivative of Primitia, that 

 it established an independent line having no subsequent connection 

 with the true Beyrichiidse and that it represents the most complex 

 stage of lobation attained by the Primitiidse. 



The Klcedenellinse are Beyrichiidae with valves more or less dis- 

 tinctly overlapping. As a rule, the overlap is confined to the ventral 

 side and ends. Beyrichiopsis Jones and Kirkby, Beyrichiella Jones 

 and Kirkby, Jonesina, and Kirkbyina, new genera, are referred to 

 the subfamily. Technically Kyammodes Jones fulfills the require- 

 ments, but, being convinced of the genetic alliance of that genus to 

 Klcedenia, the writers hesitate to remove it from the Beryrichiida?. 



CARBONIFEROUS BEYRICHIID-ffi. 



Two years ago, & the writers had occasion to discuss the Carbonifer- 

 ous Beyrichiidae. Among the conclusions were (1) that the group of 

 Beyrichia radiata is worthy of generic separation, a view carried out 

 in the present communication by the erection of the new genus IIol- 

 lina; (2) that the remaining, inequivalved Beyrichiida*, including 

 Beyrichiopsis, Beyrichiella, and Synaphe, of Jones and Kirkby, 

 besides a number of species referred by these authors to Beyrichia, 

 probably constituted a single comprehensive genus; (3) that Synaphe 

 should be relegated to synonymy under Beyrichiella; and (4) that 

 two subgenera might be recognized, of which Beyrichiopsis would 

 be one. Similar conclusions were reached in the present more com- 

 prehensive study of the family, the principal difference being that 

 Beyrichiopsis and Beyrichiella are recognized as genera, and a new 

 genus, Jonesina, is proposed instead of " a second subgenus.' 1 

 Finally, a fourth genus, Kirkbyina, is proposed for two species 

 doubtfully referred to Beyrichiella by Jones and Kirkby, and which 

 were not considered in 1906. 



"A new variety of A", clarkei is here instituted under the name of paupera of 

 which the following arc the characteristics: The valves and the ridges espe- 

 cially are thinner than in the species itself, giving the whole a somewhat 

 emaciated appearance. Furthermore, the furrows present somewhat irregularly 

 distributed hut numerous papillae which have not heeu observed in the typical 

 form of the species. See Plate XLIII, fig. 5. 



Formation mid locality. Coeymans limestone, Cumberland, Maryland. 



Holotype.—C&t. No. 53280, U.S.N.M. 



6 Proc. U. S. Nat. Mus., XXX, 1906, pp. 151-155. 



