71 



Vault ouly mtxlerately convex aud covered witli siuall, convex, 

 polygonal plates, antl bears a subcButral proboscis. 



This species Las little or no resemblance to B. modulus or B. 

 variabilis, the other two species, bearinj^ fifteen arms, described 

 from the Burlington Group. In form, it more resembles B. 

 adarnsensis, a ten-armed specit s, or B. imparilis, a twelve armi^d 

 species, or B. longirostris, au eightcen-armed species. A very 

 beautiful series of bowl-shaped species might be arranged, bear- 

 ing from ten to twenty arms. 



Found in the Burlington Group, at Sedaliu, Missouri, and now 

 in the collection of F. A. Sampson. 



BATOCRINUS SEDALIEN.SIS, n. sp. 



Plate 71', Fi(j. 31, azijj/aus sde; Fig. 32, opposite view. 



Species rather below medium size, biturbii ate, vaidt having a 

 capacity equal to or greater than the calyx. Calyx obconoidal, 

 about twice as wide as high. Plates pyramidal. 



Basals small, thin, and projecting sliglitly beyond the end of 

 the column. First primary radials about one-half wider than 

 long aud sharply pyramidal, three hexagonal, two heptagonal. 

 Second and third primary radials together very little larger than 

 the first. Second primary radials quadrangular, about twice as 

 wide as long. Third primary radials larger than the second, three 

 hexagonal, two pentagonal, axillary, and supporting, on each upper 

 sloping side, a single secondary radial, which is axillary, aud sup- 

 ports, on each upper sloping side, a single tertiary radial, which 

 gives to each ray four arms and four ambulacra! openings to the 

 vault. There are, therefore, twenty arms in this species. The 

 arm formula is 4+4-|-4+4+4. 



The azygous and regular interradial areas are cut off from the 

 plates of the vault by the union of the tertiary radials above 

 them. There are three plates in each regular interradial area, one 

 followed by two smaller ones, in the second range. There are six 

 plates in the azygous area. The first one is in line with the first 

 primary radials and larger than either one of them. It is fol- 

 lowed by three plates in the second range, one, in the third 

 range and one in the fourth range. 



