last lifinii axillary ami supportiiii;' on cacli ujiper side a tertiary 

 radial, ami <iii llie other proximal side o\w secondary radial, which is 

 axillary, and su|)ports on each upper side a tertiary radial, which 

 jlivcR to each nf tlusr twui-ays thi'ec arms. There are, therefore , 

 twelve arms in this s[)ecies. The arm fonnida is •i-{-2~\-2-\-2-{-3. 



In each of three ren'nlar int<'iTadial ai'.'as there are three plates — 

 line in the tii'sl I'anji'c and two in the second, hoth of which connect 

 \',ith the |>latrs (if the \anh; in the ntliei-area there are four plates, 

 two (if which cdnnecl with the jilatcsof Ihe \anlt. In the azyjifous 

 area there are seven plates. The first is in line with the lirst primary 

 radials and fully as laryc as either of tlicin. It is followed by three 

 plates in the second raiiLje. the middle one of which connects with 

 tjie plates of tin' \anlt. ()nthe left of the upjier part of this elon- 

 gated ])late there is one ]ilate that connects with the vault, and on 

 the riu'ht there are two plates, one of which connects with the vanlt. 

 There are. therefore, three a/.yudus plates, in a wide area, that con- 

 nect with the \anlt. 



The\anlt is pyramidal. Iiy I'cason of lieinu depressed in the in- 

 terradial areas, and hears a larn'e central proboscis. It is covered 

 with convex, polygonal (ilates. 



This species is so distinct from all other twelve-armed species, in 

 general aijpearrince as well as in the general structure, that no com- 

 parison is necessary. 



Found by R. A. Blair, in the Burlington {irroup. near Sharon, in 

 Southwest Missouri, and now in the collection of S. A. Miller. 



B.\T(X'RtNfS lU'STICELLUS. 11. Sp. 



Phifc I. Fiij. y.v. Iiamd ricir : Fiij. 10. same. Dinj/iiitied tiro iliani- 

 rfrrs; Fkj. Jd. ir.i/i/Oiis side: I'^itj. V/. sini/iinf ricir. 



\\ e Innc three s])ecimeiis of this species, one of which is twice as 

 large as the oni^ illustrated. The species, may. tlierefor(\ be said to 

 be medium or slightly below medium in size, biturbinate or some- 

 what wheel-shapetl. the larger s|)ecimen more wheel-shaped tlian the 

 one illustrated. Calyx very rapidly s])n'a(ling at the arms: where it 

 is from two to two and a half times as wide as high. No radial 

 ridges, l)ut the radial series are slightly lolied and project at the 

 margin so as to notch t he circumference at the interradial spaces. 

 Plates plane and finely graiudar. Ambulacral openings not visible 

 in a basal view, but mav be seen in a summit view. ( )iie ovarian 



