21 



This species is probably as nearly related to Archdocritm 

 sculjilus, which we suppose was collected in the same group of 

 rocks, as to any other, but the structural differences are so marked 

 that no comparison is necessary. 



Found in the Treutou Groui), iu Knox County, Tennessee, and 

 now in the collection of Win. F. E. Gurley. 



ARCH.EOCRINUS PARVUS, U. Sp. 



PUite II. Fig. 20, basal vieiv; Fi,g. 27, azijgous side view; Fig 



^S, siiiii iiiit rieic. 



Species small; calyx saucer-shaped subpentagonal in outline, 

 more than twice as wide as high; radial ridges not distinguished 

 and interrupted at the sutures; plates sculptured; surface granular; 

 columnar cavity of moderate depth and indicating by its shape a 

 pentagonal column. 



Basals suuk witiiin the calyx and showing a pentagonal outline 

 beyond the circumference of the column. Sabradials longer than 

 wide, sharply bent into the columnar cavity and upward between 

 the radials, leaving a pentagonal cavity below bounded by a sharp, 

 angular ridge, upon which the calyx may rest, showing the sub- 

 radials in a side view. 



First primary radial.s sculptured, wider than higher, pentagonal. 

 Second radials twice as wide as high, hexagonal. Third radials 

 short, pentagonal, axillary, and supporting upon each upper slop- 

 ing side the secondary radials. No tertiary radials. Ten arm 

 openings to the vault. 



First regular interradial large, sculptured and supporting two 

 plates iu the second range that separate the secondary radials and 

 unite with the plates of the vault. First azygous interradial 

 large and supporting in the second range three plates, the lateral 

 ones small; these are succeeded by three plates that unite with 

 the plates of the vault, the lateral ones uniting with the protect- 

 ing sides of the ambulacral furrows. 



Vault moderately convex and covered with jjolygoual convex 

 plates, proboscis small and subcentral. 



This species, though small and somewhat resembling A. (tsperaius, 

 is so distinct as to require no comparison to distinguish it. 



Found in the Trenton Group, iu Knox County, Tennessee, and 

 now in the collection of Wm. F. E. Gurley. 



