BRACHIOPODA. 259 



Observations. The distinguishing characters of this genus are, («) its orthoid 

 external features, and muscular scars in the pedicle-valve ; (b) the presence of 

 strong dental lamellae which are not known among the streptorhynchoids, ex- 

 cept in Meekella ; (c) the absence of any cardinal area on the brachial valve ; 

 {(1) the presence of a slight median septum in both valves. Hipparionyx proximus 

 is an abundant fossil in the Oriskajiy sandstone of New York, occurring also at 

 Cumberland, Maryland, and in the arenaceous layers at the base of the Upper 

 Helderberg in the Province of Ontario. The form from the Eifel referred to 

 this species by Schnur is regarded by Kayser* as Orthothctes umbraculum, and the 

 shells thus identified by Davidson, from the beds of Looe, Cornwall, and the 

 Budleigh-Salterton pebbles, can not belong to the Oriskany species. 



Genus KAYSERELLA, gen. nov. 



1853. Ortbis, Schnur. P;ila;ontographicii, vol. iii, p. 212, pi. xxxvii, tig'. 8; pi. xxxviii, fly. i ; p. '218, 



pi. xlv, fig. 9. 

 1871. Streptorhynchuft ? , Kayser. Zeitsclii'ift der <leiitschen grolog-iscli(>n rTesellsch.aft, vol. xxiii, p. (il7, 



pi. xiv, figs. 2 a, h, c, d, e. 



1885. StreptorhyncUus'f, Maurer. Kiilke von Waldgh-mes, p. 138, pi. v, tig. 10. 



1886. iStreptorhy7ichusf,'^Bti-iuKOFF. Faniia des Devon. Syst. iiii uordw. uml central Russl., p. 65, 



pi. ii, tig. 4. 



The species described as Orthis lepida hy Schnur, in his work on the Brachi- 

 opoda of the Eifel,f has been shown by Professor Kayser to be a streptorhynchoid 

 shell, with a covered delthyrium on the pedicle-valve and a very prominent 

 median septum in the brachial valve, dividing the internal cavity much as in 

 the Devonian forms of Scenidium, where the central plate is greatly developed. 

 This is a feature not met with elsewhere among the fossils of this group, and 

 though the internal characters of the species remain undefined, except the sep- 

 tum, this character alone must exclude it fi'om any of the generic groups now 

 recognized. That Professor Kayser recognized its generic value, is evident 

 from his language : 



" Strept. lepidus steht durch Gestalt, Form der Rippon und deutliche Perfora- 

 tion der Schale den Arten des Formenreihe der Orthis circularis zwar nahe, 



* Zeitscbr. der deutscheii geologi.scUeii Gesellschaft, vol. xxiii, p. 010. 1871. 



t Zusammenstellung und Beachreibung saniratlicher im Uebergang.sgebirge der Eifel vorkomnienden 

 Brachiopoden, nebst Abbildnngen derselben ; Palaoutographiea, lU. cit. 



