28 



BATOCKINUS (?) RUSTICUS, 11. Sp. 



Plate II, Fig. 3, basal view magnified tiro diameters ; Fig. 4, same 

 natural size; Fig. 5, azygous side; Fig. 6, summit mew. 



Species rather below medium size, calyx and vault somewhat equal 

 and together somewhat lenticular. Atnbulacral openings directed 

 horizontally and not visible in either a basal or summit view. Calyx 

 very rapidly spreading' from the basal disc, slightly depressed in the 

 interradial areas, and lobed over the radial series. No radial ridges, 

 but the radial series project so as to notch the circumference at the 

 interradial spaces. Ovarian pores not discovered. 



Basal plates very short and form a hexagonal disc bearing a con- 

 cave depression for the attachment of the column. First primary 

 radials larger than the second and third together, wider than long, 

 three hexagonal, two heptagonal. Second primary radials quadran- 

 gular, from four to six times as wide as long. Third primary radials 

 a little larger than the second, pentagonal, axillary, and the ray 

 opposite the azygous area, supports, on each upper sloping side, 

 three secondary radials, which gives to this ray two arms. In each 

 of the other four arms, the third primary radial supports, on each 

 upper sloping side, two secondary radials, the last being axillary 

 and supporting, on each upper sloping side, two tertiary radials, 

 which gives to each of these rays four arms. There are, therefore, 

 eighteen ambulacral openings to the vault, in this species. The 

 arm formula is 4 4 2 4 4. 



There are three plates in each regular interradial area, one in the 

 first range, followed by two narrow elongated plates, in the second 

 range, that unite with the plates of the vault. In the azygous area 

 there are six plates. The first is in line with the first primary ra- 

 dials and narrower and smaller than either of them. It is followed by 

 three plates, in the second range, and two in the third range, that 

 unite with the plates of the vault. 



Vault convex and bears a rather large, convex, central plate, sur- 

 rounded by seven plates, three of which adjoin the small plates that 

 surround the azygous orifice. The plates over the ambulacral canals 

 are large and tumid, those in the interradial areas smaller and less 

 convex. The azygous orifice is small, somewhat elevated, and sub- 

 central. 



