Missouri Palaeontology. — Rowley. 307 
umn and leaves no doubt of the correctness of the reference. The 
stem segments are very thin and of uniform diameter, together form- 
ing a perfectly smooth column. 
Third division of the Lower Burlington limestone, Cole's 
quarry, Louisiana, Mo. 
Metablastus bipyramidalis Hall. 
Fig. 28 is a small specimen preserving the delicate pinnules. It is 
from the Keokuk beds at Boonville, Mo. 
Metablastus lineatus Shumard. 
Fig. 29. Side view of a small specimen from the third division of 
the Lower Burlington limestone. The specimen is from the soft white 
chert and preserves the test. 
Fig. 30. Side view of a natural cast from the Upper Burlington 
chert. 
These two figures are intended for comparison with other 
species of Burlington blastoids of the elongate form, figured on 
this plate. 
Figure 29 is beautifully striate under the lens. A cast of 
this species in our collection is over two inches long and in 
size rivaled either zvortheni or bipyramidalis. 
Burlington limestone, Louisiana, Mo. 
Codaster gracillimus Roiwley. 
Figures 31, 32. Side views of the type and a much smaller specimen/ 
natural size. 
These specimens are figured here for comparison with other 
elongate forms. Like Codaster grandis, C. laeviculus and the 
new form, C. superhus, this species has hydrospire slits in all 
five of the interambulacral areas and, according to Ethridge 
and Carpenter's classification, would be a Phaenoschisma. The 
surface is beautifully striate and the specimens came from the 
soft white cherts of the third division of the Burlington, Pratt's 
and Cole's quarries. 
The chief characteristics of this species are its slender form 
almost flat ventral region, narrow ambulacra, very fine hydro- 
spire slits, very elongate basal plates (from a half to two-thirds 
the length of the fossil), sharply angled character of the baso- 
radial sutures at their junctions. 
Mesoblastus kirkwoodensis? Shumard. 
Fig. 33. Side view of a small but plump specimen. 
Fig. 34. Ventral view of the same specimen. 
