Missouri Palaeontology. — Rowley. 309 
the upper part of the Upper Burlington limestone, much above 
the horizon of C. grandis. 
The type specimen is quite an inch and a quarter long and 
much the finest species of the genus. 
Upper Burlington chert, Louisiana, Mo. 
Codaster laeviculus Rowley. 
Fig. 37. Side view of a specimen, a little flattened, as it lies partly 
imbedded in soft earthy limestone. 
Fig. 38. A typical natural cast of this species from chert. 
Fig. 39. Side view of a natural cast from chert, probably a variety 
cf this species. 
Cadaster laeviculus differs from the other Burlington spe- 
cies of this genus, greatly, in its broad, petaloid ambulacra 
covering completely the hydrospire slits, and in the possession 
of five rather large heart-shaped openings at the junction of 
the ambulacra, near the central opening. 
It is doubtful whether it could be ranged under Phaeno- 
schisma. This is rather a puzzling form, possessing character- 
istics of several genera. 
It occurs in the very basal layer of the Upper Burlington 
limestone and cherts of the same horizon. 
Specimen 37 is from Pratt's quarry, Louisiana, Mo, 
Codaster grandis Rowley. 
Figs. 40 and 41. Side and summit views of a medium sized speci- 
men. A natural cast from chert. 
This is a very handsome species and is figured here to com- 
plete the Burlington species of the genus. 
Its rotund form with a broad ventral surface and slender 
ambulacra at once separate it widely from the other Burling- 
ton species. 
Three limestone specimens came from the basal layer of 
the Upper Burlington limestone in Pratt's quarry, while the 
specimen here figured was found near Curryville, Mo., and the 
type specimen from a chert on the hillside, west of Louisiana. 
While there is some resemblance in outline between Codas- 
ter laevicuhis and C. snperhus, the latter has many more hydro- 
spire slits to the area than the former, and, in fact, more than 
any other Burlington species, except C. grandis. The narrow 
