536 Breger — Eodevonaria, a new Subgenus of Glionetes. 



Lower Devonian in Bolivia,* in Argentina, f and in South 

 Africa^ in a fauna which is certainly that of some part of the 

 Coblentzian and only very slightly if at all higher than the 

 Gaspe" fauna with Chonetes melonicus. The crenulated hinge 

 line has been figured by Thomas. 



All these species are medium to large-sized Chonetes, with 

 gibbous to very gibbous pedicle valve and a concave brachial 

 valve ; with a large number of medium fine radial striae ; and 

 with the usual hollow spines along the posterior margin ; — 

 all features of normal Chonetes. As in normal Chonetes, 

 there is a wide cardinal area, quite prominent in the pedicle 

 valve, less so in the brachial. The delthyrium is covered with 

 a pseudodeltidium. Very narrow and short diverging lamellae 

 support the teeth. The diductor muscles in the pedicle 

 valve of C. {Eodevonaria) arouata leave two broadly diverging 

 isolated oval scars, while between them in the center may be 

 seen the subcircular or elongate-oval scar left by the large 

 adductor muscles. The latter scar is divided in two by a 

 median septum. The median septum is present in the pedicle 

 valve in all the species of Eodevonaria, as in all the Chonetes. 



The precise nature of the denticulations on the hinge line 

 in Eodevonaria cannot be stated just now. Whether these 

 denticulations alternated with each other in the two valves 

 to assist in articulation as in the Stropheodonta's ; whether the 

 denticulations represent the bases of vertical tubes as in 

 Anoplia; whether they are points of insertion or of division of 

 a ligament or other membrane which probably covered 

 the cardinal area in the brachiopods (compare the divided liga- 

 ment in Pema, Cervillia, Inoceramus, and the other genera 

 of Pernidae among the lamellibranchs) ; or whether they 

 served some other purpose, will be known when better material 

 than is now at hand becomes available. 



* A Ulrich, Palaeozoische Versteinerungen aus Bolivien. Neues Jahrb. 

 f. Mineralogie, etc., Beilageband VIII, p. 77, PL IV, figs, 35, 36, 1892. 



\ 1. Thomas, Neue Beitrage zur Kenntnis der devonischen Fauna 

 Argentiniens. Ztsehr. d. Geol. Ges., vol. lvii, p. 258, PL XIII, fig. 26, 1905. 



%¥. Keed, Brachiopoda of the Bokkeveld Series. Annals of the South 

 African Museum, vol. iv, Part III, p. 173, PL XXI, fig. 3, 1904. The South 

 African specimens may not belong to Ulrich's species, nor possibly to the 

 present subgenus. 



