68 PALAEONTOLOGY OF NEW YORK. 



had given excellent figures, showing very completely the characters of the 

 pedicle- valves of 0. desquamata (= 0. crassa. Hall), and 0. gemma, Billings. 

 But in 1863,* the interiors of both valves of Oboklla? polita, Hall, had been 

 illustrated, and the figure given of the pedicle-valve (there termed " dorsal ? ") 

 represents the impressions almost precisely as we now know them to be in the 

 corresponding valve of 0. chro?natica, 0. crassa, and others ; while those of the 

 opposite valve, usually less distinctly retained than in the pedicle-valve, show 

 the long, curved laterals and the central scar. (See further under discussion 

 of DiCELLOMUS.) Ill 1881, Mr. Fordj demonstrated the interior characters of 

 the brachial valve of 0. crassa, subsequently amplifying his observations some- 

 Avhat in a figure published by Mr. Walcott in Bulletin No. 30, 1886. In this 

 work, Mr. Walcott also gives a figure of the interior of the same valve of 

 0. chromalica, demonstrating the complete harmony of its scars, both in 

 arrangement and development, with those of 0. crassa. The same author 

 gives, in addition, illustrations of the interiors of O. gemma, and 0. Circe, 

 Billings. 



The genus Obolklla possesses, as far as known, a larger specific representation 

 than any other group of primordial brachiopods, but all species that have been 

 referred to the group are not congeneric. The true Obolella, as far as it is 

 accurately known, is not only confined to primordial faunas, but is believed to 

 be largely American in its representation. The forms referred by English 

 writers to the genus fail to show the characteristic generic features. Some 

 of them have already been assigned to other genera, e. g., 0. sagittalis, Salter, 

 to LtNNARSSONiA, Walcott, to which genus probably belong 0. Belli, Davidson, 

 and O. maculata. Hicks ; 0. Sabrina, Callaway, will undoubtedly prove a repre- 

 sentative of a distinct genus, its relations to Acrotreta having been pointed out 

 by Mr. Walcott. 



Certain of M. Barrande's species show internal features indicating their 

 close alliance to Obolella, e. g., Lingula Feistmanleli,X Obolus? complexus,^ Obolus 



* Hall. Sixteenth Rept. N. Y. State Cab. Nat. Hist. (he. cit.). 



t Araei-ican Journal of Science, vol. xxi, \\. 131. 



X Sys^t. Sil. Bohcme, vol. v, pi. lOG, fiy. iv. 



§ Syat. Sil. Boheme, pi. 9;"), tig. iii ; pi. Ill, lig-. vi ; pi. 152, fig', ii, 4. 



