126 KANSAS UNIVERSITY QUARTERLY. 



Oligoporus? minutus, n. sp. Plate XXXII, Fig 3. 



Small, depressed globular, melenitic ridges not very distinct. 

 There are four columns of pores, each column consisting of two 

 rows in each ambulacral area, each row consisting of two rows of 

 pores, the rows of each column closely arranged. Each series 

 is apparentl}^ separated by a row or two of imperforate plates at 

 the ambitus. Both series are in contact at the apex? and near the 

 mouth?. Number of columns of interambulacral plates unknown, 

 but apparently about three. The ambulacral area is very wide 

 and the two series are widely separated at the ambitus. Some of 

 the elevations on the interambulacral plates seem to be pierced by 

 a single pore or sometimes two. Indistinct elevations seem to be 

 present in three columns, one of large and two of small size. 



Measurements: 



Diameter of specimen , 23 mm. 



Maximum diameter of ambulacral area 6 



Maximum diameter of each series 2 



Maximum diameter of interambulacral area 7 



Pores in vertical rows 



Pores distant in same series 1 1^ 



Pores in single pair y^ 



The specimen is badly worn and somewhat compressed; the sur- 

 face markings are almost entirely removed. It agrees to some 

 extent with Oligoporus, but the ambulacra are divided into two series 

 with, apparentl)'^, two columns of imperforate plates between them. 

 However, this is not unquestionably shown by this specimen. It 

 will in all probability be found to belong to an entirely different 

 genus. It is referred to Oligoporus for convenience, until better 

 material can be secured. It does not seem to present the appear- 

 ance of any other Carboniferous genus. 



It was collected from the Deer Creek limestone northeast of 

 Topeka, Kansas. 



Posidonoraya? recurva, n. sp. Plate XXXII, Fig. 6. 



Shell of medium size, lenticular, oblique, and thin. The hinge 

 line is nearly straight, about two-thirds the length of the shell. 

 The beak is moderately prominent, recurved, projecting very 

 slightly beyond the hinge. The greatest convexity is on the upper 

 half of the shell and constitutes the umbonal swell which is mader- 

 ately prominent and curved backward, making the shell oblique. 

 The surface is marked by concentric undulations of growth and 

 fine, closely set, concentric striae. 



