40 Trans. Acad. Sci. of St. Louis. 



6. Oligoporus parvus. Hambach. 



1884. Oligoporus parvus. Hambach, Trans. St. Louis Acad. 



Sci., vol. 4, p. 550, pi. C, fig. 3. 

 1889. Oligoporus parvus. Miller, N. Amer. Geol. Pal., 



p. 263. 



1894. Oligoporus parvus. Keyes, Mo. Geol. Surv., vol. 4, 

 p. 127. 



1895. Oligoporus parvus. Keyes, Proc. Iowa Acad. Sci., 

 vol. 2, p. 183. 



Interainbulacra composed of five columns of plates each, 

 nearly one- third wider than the ambulacral areas. Ambu- 

 lacra narrow with an elevated ridge in the center. Each 

 plate has two pores near the outer margin, giving two double 

 rows of pores to each side of the ridge. Plates coarsely 

 granulated and covered with fine short spines. 



Geological formation and locality: St. Louis Limestone, 

 St. Louis, Mo., and Hardin Co., Ky. 



INSUFFICIENTLY DETERMINED SPECIES. 



1. Oligoporus? minutus Beede. 



1899. Oligoporus? minutus. Beede, Kas. Univ. Quart., ser. 

 A, vol. 8, no. 3, p. 126, pi. 32, fig. 3. 



1900. Oligoporus? minutus. Beede, Univ. Geol. Surv. Kas., 

 vol. 6, p. 49, pi. 7, fig. 3. 



Geological formation and locality : Deer Creek Ivime- 

 stone, northeast of Topeka, Kas. 



d. Melonites Owen and Norwood 1846.* 



Syn. Melonechinus Meek and Worthen 1860. f 



Melechinus Quenstedt 1875. t 



From five to nine (sometimes more) columns of plates in 

 each interambulacrum and ten columns in each ambulacrum. 

 Two rows of pores to each ambulacrum. 



* Amer. Journ. Sci., ser. 2, vol. 2, p. 225. 



t Proc. Acad. Nat. Sci. Phil., p. 396. 



X Petref. Deutschl., abth. 1, bd. 3, p. 381, pi. 75, flgs. U-50. 



