STATE GEOLOGIST. 107 



212. Productus, sp? 



A species destitute of radiating striae or ribs. The ventral 

 valve shows five or six varices or lines of growth • the dor- 

 sal, (if it is the same species) more than this. The surface- 

 is punctate. 



It is allied to P. gryphoides DeKoninck, (Op. cit. p. 182, 

 PI. IX., Fig. 1, but not to the other figures.) 



Locality — Grand Eapids. 



213. Productus, sp ? 



Considerably resembles in form and size, P. muricatus, Nor- 

 wood and Pratten, from the coal measures, but the radiating 

 ribs are too fine. It is somewhat like DeKoninck's figure of 

 P. costatus, (PI VIII., Pig. 3,) but is not sinuated. It closely 

 corresponds with P. costatus from tbe coal measures, 9 miles 

 north of St. Louis, Mo., except in not being sinuated, and in 

 the less conspicuous character of the concentric rugss. 



Locality — Grand Eapids. 



214. Productus, sp? 



Has the form of the last, but the radiating striae are much, 

 finer and the concentric folds little conspicuous. 



Locality- — Grand Rapids. 



215. Orthis umbraculum (?) von Buch. 



Allied to 0. robusta, Hall, (Op. cit. 713.) Resembles 0. um- 

 braculum as figured by DeKoninck, (Op. cit. p. 223,) from 

 carboniferous limestone, but better as figured by Owen, (Op. 

 cit., Tab. V., Fig. 11.) It exbeedingly resembles this species 

 as figured by Hall in Stansbury's Report, (PI. Ill, Fig. 6.) 



Locality — Grand Rapids. 



216. Orthis (?) sp? 



A single flat valve with slender auriculate appendages ex- 

 tending the hinge line to nearly the greatest width of the 

 shell. 

 Locality — Grand Rapids. 



232. Orthis, sp ? 

 A single dorsal valve more finely striate than the preceding. 



Locality — Stone Island, in Saginaw Bay. 



217. Athyris subquadrata, Hall, (Iowa Rep., 703.) 

 This species is from the Kaskaskia limestone. 

 Locality— Grand Rapids. 



218. Athyris sublamellosa, Hall, (Iowa Rep., p. 702.) 



Agrees pretty well, but the shell is not more than one-third 

 the dimensions of Hall's, and is proportionally a little thinner. 

 This species is from the Kaskaskia limestone. 



