115 [S 



ENATE 



PROETUS DORIS (n.s.). 



The caudal shields of a species of this genus are not rare in the same association 



with the preceding fossils. 



Caudal shield semielliptical, convex; the axis gibbous, rounded and very promi- 

 nent in old specimens, obtuse posteriorly. The plain border of the pygidiuin is 

 about half as wide as the lateral lobe, and defined by a shallow depression on 

 the inner side, marked by about eight ribs, while the axis is marked by thirteen 

 or fourteen in full grown specimens. Surface granulose. 

 This species is larger than the one in the Goniatite limestone in New-York. 

 Geological formation and locality. In the Goniatite limestone at Rockford, 



Indiana. 



I am aware that this enumeration of species shows a large preponderance of 

 numbers in the Indiana locality; and that viewed together, these might be re- 

 garded as evidences of the existence of a Carboniferous fauna in that region dur- 

 ing the period of the deposition of these beds. On the other hand, the Goniatites 

 of the New- York rocks, including those of the Hamilton group, offer too close an 

 analogy to be referred to a different system of strata. 



The absence of Gomphoceras in the Indiana locality is a striking fact, while 

 Gtroceras is barely represented in the collections. It is not improbable that 

 further examinations may reveal these and other fossils in the same beds. It should 

 not be forgotten, also, that the same limestone, in the Marcellus shale of New- 

 York, in localities where the Goniatites do not occur, yields numerous fossils 

 not here enumerated. Even admitting that the fauna of the Goniatite limestone of 

 Indiana has a more carboniferous aspect, it is only in accordance with what we 

 observe in other strata above the Upper Helderberg limestones as we trace them 

 in a westerly direction. This subject, however, will be resumed in a future report. 



I have been indebted, for specimens from Rockford, to Mr.H.C. Grosvenor, 

 and Mr. S. T. Carlet of Cincinnati, Ohio, and to Mr. S. S. Lton of Jeffersonville, 

 Indiana. The most numerous collection of species, however, was made by Mr. A.H. 

 WoRTHEN during his connection with the Iowa Geological Survey, while making 

 a section across the country from the Mississippi river to the outcrops of the 

 lower strata bordering the Cincinnati axis. 



CORRECTION. 



The reader will please alter the names Orthisina arctostriata and 0. alternata, 

 on pages 80 and 81, to Streptorhynchus arctostriata and S. alternata; the species 

 having been inadvertently left under the former genus to which they were origin- 

 ally referred. 



