534 Breger — Eodevonaria, a new Subgenus of Chonetes. 



Art. XLYIII. — On Eodevonaria, a new Sub- Genus of Cho- 

 netes ; by C. L. Breger. 



Among the Strophomenoid Brachiopoda, the presence of a 

 crenulated or denticulated hinge line has always been consid- 

 ered as of at least generic importance. It was upon this con- 

 sideration that the genus Stropeodonta was founded by Hall ; 

 and it is chiefly or very largely the presence of a denticulated 

 hinge line which sharply demarcates as a special group apart 

 from the normal Strophomena's the genera Stropheodonta,. 

 Douvillina, Leptostrophia, Braehyprion and Strophonella* 



In the well-known Paleozoic genus Chonetes, the great mass 

 of the species have a normal, non-crenulated hinge line ; but, 

 as is the case with the Strophomenoids, there occur a few 

 closely associated and quite peculiar species in which the den- 

 ticulated hinge line is a very prominent and characteristic 

 peculiarity. It has been found than such a denticulated hinge 

 line occurs in six species of Chonetes. All six species are so 

 closely allied as to be distinguishable only with some little 

 difficulty ; and all six species occur at very nearly the same 

 geologic horizon in the Lower Devonian, though scattered 

 through Europe, South Africa, South America, and North 

 America. These facts justify setting this group apart from 

 the normal and typical species of Chonetes, and the name 

 Eodevonaria is hereby proposed for this group. The name is 

 suggested by the restriction of all the known species (as well 

 as a few more which it is believed may possibly belong here) 

 to the Eo-Devonian. The known species are 



1. Chonetes arcuatus Hall 



2. C. dilatatus F. Roenier's sp. 



3. C. melonicus Billings 



4. C. acutiradiatus Hall 



5. C. extensus Kayser 



6. C. arcei A. Ulrich 



1. Chonetes (Eodevonaria J arcuatus. — The crenulated 

 hinge line in this type was noted by Hallf in his description 

 and illustrations of the species. Weller also noted the same 

 features in New Jersey specimens of this species. J Chonetes 

 (Eodevonaria) arcuatus occurs in the Upper Helderberg 



* For descriptions of these genera, see Paleontology New York, vol. viii, 

 Pt. I. 



f Hall, The Fossil Brachiopoda of the Upper Helderberg, Hamilton, Port- 

 age and Chemung group. Paleontology of New York, vol. iv, p. 119, PI. 

 XX, see figs. 7e, 7f, 1867. 



% Weller, The Paleozoic Faunas of New Jersey. Paleontology of New 

 Jersey, vol. iii, pp. 367, 373, PI. LI, fig. 21, 1903. 



