LOWER CARBONIFEROUS FOSSILS. 535 



Productus semireticulatus Martin. 

 PI. LXIX, figs. 8a, 8Z>, 8c, 8d. 



Anomites semireticulatus Martin, 1S09: Petrefacta Derbiensia, p. 7, PL XXXII, figs. 

 1, 2; PL XXXIII, fig. 4. 



Productus semireticulatus Xorwood and Pratteu, 1854: Jour. Acad. Xat. Sci., 2d series, 

 Vol. Ill, p. 11. Hall, 1858: Geol. Surv. Iowa, Vol. I, Pt. II, p. 637. Meek, 1872: 

 Final Rept. U. S. Geol. Surv. Xebraska, p. 160, PL V, figs, la, lb. White, 1875 : 

 Wheeler's Expl. Surv. W. 100th Merid., Vol. IV, p. Ill, PL VIII, fig. 1. Meek 

 1S77: King's U. S. Geol. Expl. 40th Par., Vol. IV, p. 69, PL VII, fig. 5. Hall 

 and Whitfield, 1877: ibid., p. 267, PL V, figs. 5, 0. L>awson, 1878: Acadian 

 Geol., 3d ed., p. 296, fig. 97. White, 1884: Thirteenth Rept. State Geologist 

 Indiana, p. 125, PL XXIV, figs. 1-3. Herrick, 1885: Bull. Denison Univ., Vol. 

 Ill, p. 31, PL I, fig. 26; PL III, fig. 24; PL VII, fig. 11: PL X, fig. 6. Hall and 

 Clarke, 1892: Pal. Xew York, Vol. VIII, Pt. I, PL XVIlA,figs. 16-18; PL XVI II, 

 figs. 11-13; PL XIX, figs. 19-23. Keyes, 1S95: Geol. Surv. Missouri, p. 50, PL 

 XXXVI, fig. 4. 



The specimens assembled under this name come from a number of 

 localities and present considerable variation. Taken as a whole, the size 

 is smaller and the beak more attenuated than specimens from the Coal 

 Measures often show. The median sinus, which often constitutes a marked 

 character in those forms, is either indistinct or not developed at all, while 

 the concentric wrinkles, which produce along the striae the characteristic 

 reticulate appearance, are less strongly marked and are confined to a more 

 limited area. 



The ventral valve figured (PI. LXIX, figs. 8a, 8b, 8c) is distinctly more 

 coarsely striate than other individuals from the same locality, while material 

 from other localities is more finely striate still. The figured specimen has 

 about ten stria? in 10 mm. along the margin, while others, perhaps the 

 greater number, have about fifteen. Again, the dorsal valve (fig. 8(f) is, 

 though quite large, nearly flat over its entire area. This specimen has a 

 transverse diameter of about 33 mm., while other individuals, only 23 mm. 

 across, already show a well-marked geniculation. These data show about 

 the character and range of the variation observed. 



A form identical with this occurs in the Chouteau limestone at Black 

 Water, Saline County, Missouri ; Chouteau Springs, Cooper County, Missouri, 

 etc; and in the Cuyahoga shale of the Waverly group at Richfield, Summit 

 County; Bagdad, Medina County, etc. It is closely related, perhaps 

 identical, with P. flemingi var. burlingtonensis, as identified by Hall and 



