﻿NORWOOD AND PRATTEN ON PRODUCTI. 21 



Fig. 1, b. Profile view of an older specimen. 

 Fig. 1, c. Same, showing the relations of the two valves. 

 Fig. 1, d. A young individual of the same species. 



Fig. 1, e. Magnified view of the spines and tubercles on an adult specimen, to 

 show their arrangement. Illinois State Collection. 



Section VII. 

 PRODUCTI CAPERATI. 



P. Murciiisonianus, de Koninch. — De Koninck " On the Genus Productus." PL 

 XVI., fig. 3. 



Geological Position and Localities. — Devonian limestones of the Devil's Back Bone, 

 Illinois ; and upper Silurian beds of Madison, Indiana. Illinois State Collection. 



P. subaculeatus, Murclvisoii. — De Koninck " On the Genus Productus." PI. XVI., 

 fig. 4. 



Geological Position and Localities. — Devil's Back Bone, Illinois ; Graham Creek and 

 Lewis Creek, Indiana, in Devonian limestone. Illinois State Collection. 



P. Nebeascensis, D. D. Owen. — " Report of a Geological Survey of Minnesota," 

 etc. Tab. V., fig. 3, p. 584. 



Locality. — Crossing of the Big Nemahaw, Nebraska Territory. H. Pratten's col- 

 lection. 



P. Granulosus, Phillips. — " Geology of Yorkshire," vol. ii., p. 216. PL VIII., fig. 

 15 ; and de Koninck's " Monograph " on the genus, p. 135, pi. XVI., fig. 7, a, b, c. 



We have received this shell from Mr. Worthen, who found it at Nauvoo, Illinois, 

 and from Jas. Husbands, who found it at Carrsville, Kentucky. It occurs at both 

 localities in the mountain limestone. At Nauvoo, in the middle portion of the series ; 

 at Carrsville in the upper part. 



