78 PALMONTOLOGY OF NEW YORK. 



The opposite valve shows the very peculiar feature mentioned by Mr. 

 Billings, a thickened area in the umbonal region presenting the appearance of 

 a false cardinal area inside the cavity of the umbo, a character which is sug- 

 gestive of that in Ltngulasma, but evidently of different function. This area 

 is tripartite, bearing a deep, narrow central and two broader lateral grooves ; 

 about its anterior margin lie two broad scars of the same character as the 

 laterals of the other valve. There are also seen the diverging furrows, which, 

 starting at the marginal apex, pass over the edge of the thickened area, and 

 are most deeply impressed at their anterior extremities. 



To homologize the musculnr features seen in Elkania with those of Obolella 

 or any allied genus, is a difficult matter. Mr. Fokd was disposed to regard the 

 central depression of the pedicle-valve as an extravagant development of the 

 pedicle-pit seen in 0. crassa and 0. chromatica. This appears very plausible, 

 but complicates the correspondence of the other scars ; and, moreover, as the 

 internal scars of the opposite valves do not essentially differ in their number 

 and arrangement, it would compel the assumption of a pedicle-pit in the 

 brachial valve. Mr. Foed has suggested that Walcott's species, Obolella ? am- 

 bigua* from the " Pogonip group " of Nevada, is congeneric with E. desiderata. 

 Mr. Walcott's figures, 2 a, 2e, of the interior of the pedicle-valve, indicate the 

 unquestionable correctness of this reference. 



Genus PATERULA, Barrande. 1879. 



I'LATE IV K, FIG. 1. 



1S79. Pafer!t?a, Barkandb. Systems Silmien dii Centre de la Boheme, voL v, p. 110, pL '95, figs, i, 



1-3 ; pL 152, fig-s. i, 1-9. 

 1S84. Paterula, Davidson. General Summai-y to British Fossil Brachiopoila, p. 391. 



Diagnosis. "Les deux valves, circulaires ou faiblement ovalaires, ne pre- 

 sentent qu'un bombement tres peu prononci' vers I'exterieur. L'espace interne 

 devait done etre tres exigu. 



" Ces deux valves se rencontrent habituellement isolees. Cependant, nous 

 figurons PI. 152, deux specimens de valves juxtaposees, qui paraissent avoir 

 appartenu a un meme individu. Nous pauvons ainsi constater, qu'il n'existe. 



* Palaeontology Eureka District, p. 67, pi. i, fig. 2. 



