106 REPORT OF THE 



broad enough for this variety, and has no mesial sinus 

 though apparently flattened. It also resembles P. costatus, 

 Sow. (DeKoninck, Carbon Foss. Belg. p. 164,) but it is not 

 broad enough nor does it exhibit any granulations. The 

 striation of some specimens is exceedingly like that of P. 

 comoides, Sow. (Phillips, Geol. Yorkshire, PI. VII, Fig. 4,) P. 

 Altonensis is from the upper portion of the Carboniferous 

 limestone, (St. Louis Limestone of hi all.) 



Locality — Grand Rapids. 



208. Productus pileiformis, McChesney (New Pal. Foss. p. 40). 

 It bears some resemblance to P. ovatus, Hall, but the stria? 

 are too fine. It differs in the same way from P. Altonensis, 

 and is, besides, broader than that species. From P. tenuicos- 

 tus, Hall, it differs from the mode of increase of the stria? 

 which is by intercalation instead of bifurcation. The con- 

 centric rugae, moreover, are not sufficiently conspicuous. 

 P . pileiformis is from the Kaskaskia Limestone. 



Locality — Ferris' limekiln, 2 miles north of Jackson. 



209. Productus. 



This was thought by Prof. McChesney, (without making di- 

 rect comparison) to be his P.fasciculatus (Op. cit. p. 38). It 

 does not, however, agree sufficiently well. 



It has some resemblance to P. Cora, D'Orbigny, as figured 

 by Owen (Op. cit. Table IV, Fig. 1), but my specimen ex- 

 hibits seven or eight ribs raised higher than the intervening 

 ones. The surface is covered by fine undulating concentric 

 striae, and when exfoliated, shows numerous punctate de- 

 pressions beneath. The spine bases are very scattered on the 

 ventral valve. 



Locality — Unknown. Supposed to be with preceding. 



210. Productus Wilberanus (?), McChesney. 



The agreement is moderately good, but the concentric stria- 

 or rugae are not generally distributed. This species comes 

 from the coal measures of Charboniere, Mo. It differs from 

 P. scabriuscvlus, DeKoninck, (Op cit, PI. IX., Fig. 5,) by the 

 irregular disposition of the pustules. 



Locality — Unknown. Supposed to be with the preceding. 



211. Productus, sp ? 



A delicate species much too finely striated for P elegans, Nor- 

 wood and Pratten, and somewhat too much so for P. Altonen- 

 sis, while it is too regularly and coarsely striate for P. pilei- 

 formis. 



Locality — Stone Island, in Saginaw Bay. 



