Bkedk.| Carboniferous Invertebrates. 79 



there are no spines. r Beak extending back of the hinge, produc- 

 ing a concavity below. Proboscis not visible from exterior of 

 complete specimens, only a minute projection seen fitting into 

 a small notch in the hinge of the other valve. The entire inner 

 surface of the valve coarsely punctate, except the portion oc- 

 cupied by the brachial and adductor markings. Proboscis pro- 

 jecting, obovate in outline, trifid, at the base of which there 

 are three radiating ridges ; two high lateral ones, which roll 

 slightly backward, extend nearly to the ears, where they fade 

 out ; the third ridge extends directly forward, smaller and 

 sharper than the others, to the anterior portion of the fiat sur- 

 face, where it ends abruptly. Situated about one-third, or less, 

 the distance from the posterior to the front of the flat surface 

 and close to the mesial ridge are the arborescent adductor 

 markings, triangular to elliptical in outline. The brachial 

 markings extend nearly directly outward from the anterior end 

 of the adductors, then bending forward and expanding, ap- 

 proaching very close to the antero-lateral extremity of the flat 

 surface of the valve. The front inner portion of these mark- 

 ings extends forward to the anterior end of the mesial ridge, 

 the posterior portion connecting with the front of the adductor 

 scar. In some specimens the brachial area is finely crinkled, 

 as are some other parts of the surface back of the muscular 

 scars. There are sometimes short, sharp pustules on the front 

 curve of the valve. Length, hinge to front, 40 mm. ; width, 

 58 mm. ; convexity, 40 mm. 



Range and distribution : Upper Coal Measures ; Kansas City, 

 Lawrence, Lecompton, Topeka, Alma, Marys ville, etc. Com- 

 mon throughout the Coal Measures of the United States and 

 the world. 



Productus costatus. Plate IX, fig. 8: plate X. figs. 1 lc; plate XI, fig. 4. 

 Productus costatus Sowerby? Min. Con., vi, p. 11."), pi. dlx, f. 1, (1827). 

 Prod aft us costatus de Koninck, Recher. Aoim. EToss., pt. i, p. D2, pi. vm, 



f. :;. pi. \. f. .'}, pi. vii, f. 3, <1S47,: Mock, Kin. Rep. U. S. Geol. Surv. 



Neb., p. 159, yil. vi. f. 6, I 1852); Sail and Clarke. Pal. N. Y., vm, pt. i, 



pi. xix, ff. 8-13, (1892); etc. 

 Productus portlockianus Norwood .and Pratten, Jour. Acad. Nat. Sri. 



Phil., in, p. 15, pi. i, f. 0. i 1854). 

 Productus uiminatis White, Proc. Boston Soc. Nat. Hist., ix, p. 2'.), i 1802). 



