18 



radials are longer than wide and the larger plates of the calyx. 

 The second primary radials are small, leaving comparatively 

 wide interradial areas. The secondary and tertiary radials are 

 short. 



Some of the arms are well preserved and others torn into 

 pieces. There are, as it appears, twenty very long, compound, 

 ponderous arms, remarkable for their expansion, in the upper 

 part. There are also twenty arm openings to the calyx. There 

 are three single, short plates in the commencement of each arm; 

 these are followed by a double series of interlocking plates that 

 are deeper than wide, making the arm in the lower part deeper 

 than wide. The arms gradually widen externally until they are 

 about four times as wide as deep. In the lower part of the 

 arms the arm furrows are shallow and the arms are twice as 

 deep as wide, they do not increase, in depth, in the upward ex- 

 tension, even where they are four times as wide as deep. 



This species is distinguished from all others by the thin, 

 smooth, slightly convex plates of the calyx and by the re- 

 markably heavy arms. 



Found in the upper layers of the Burlington Group, near 

 Burlington, Iowa, and now in the State Museum, at Springfield, 

 Illinois. The specific name is in honor of one of the founders of 

 the genus, the late distinguished palaeontologist, Sidney S. 

 Lyon, of Jeffersonville, Indiana. 



BATOCRINUS LYON ANUS, n. Sp. 



Plate III, Fig. 4, view opposite the azygous area; Fig. 5, 



basal view. 



Body above medium size. Calyx basin shaped, and spreading 

 horizontally from the secondary radials; two and a half times 

 as wide as high; plates thick, angular; sutures beveled; arm 

 openings directed horizontally. Vault conical, nearly as large 

 as the calyx, covered with polygonal, tumid plates and having 

 a large subcentral proboscis. 



Basa ] s short, more than three times as wide as high and ex- 

 cavated below, so the concavity has a depth greater than the 

 external height of the plates. First primary radials one and a 

 half times as wide as high. Second primary radials quad- 

 rangular, half as large as the first, and only a little wider than 



