DESCRIPTIONS OF THE SPECIES. L'lO 



seen so many intermediate gradations between the two thai we can only look upon 

 them as the extreme limits of one very variable species. 



It is not impossible that such a form as that now referred to may have represented 

 Troost's Olivanites globosus. 



Locality and Horizon. Columbus, Ohio (Presented by Prof. II. A. Nicholson, M.D.): 

 Corniferous limestone, Lower Devonian. Clarke County, Indiana: Upper Helder- 

 berg Group, Lower Devonian. 



EluEACBINUS ANGULARIS, Lf/OV, sp. 



(PI. II. figs. 43, 44.) 



Olivanites an ffularis, Lyon, Owen's 3rd Report Geol. Survey Kentucky, 1857, p. I'*'-', t. 5. 



f. 2 a-b. 

 Nucleocrinus annularis, Lyon and Casseday, Proc. American Assoc. Adv. Sei. 1859, vol. iv. 



p. 295. 

 Elceacrinus angularis, Shumard, Trans. St. Louis Acad. Sei. L865, vol. ii. no. 2, p. 3G8. 

 EUeacrinus angularis, E. .V- C, Ann. & Mag. Nat. Hist. 1883, vol. xi. p. 231. 



>'y. Char. Calyx pentagonal-subovoid, inflated along the lines of the ambulacra : 

 summit flattened; base contracted; section pentagonal, the sides concave; periphery 

 a little more than a third from the summit. Deltoid plates ellipsoidal, concave below 

 but becoming flattened towards the summit ; each plate divided into three parts by 

 two impressed lines diverging from the upper end, and leaving the central spaces 

 lanceolately triangular ; radio-deltoid sinuses very narrow, and much arched. Ambu- 

 lacra similar, and protruding above the edges of the sinuses. Spiracles slit-like. 

 Central summit-plates very small, and numerous. 



Remarks. We are unable to afford further particulars of this species from the fact 

 that our only specimen is imperfect, and partially imbedded in limestone. Three 

 ambulacra and the corresponding interradial areas, with a portion of the summit, are 

 all that is exposed. The pentagonal section and the great arching of the ambulacra, 

 however, clearly indicate its specific identity with Lyon's type. 



Locality and Horizon. Unknown. [Lyon gives the Falls of the Ohio, Kentucky ; 

 Beargrass and Silver Creeks, Clare County, Indiana: Lower Devonian, as the localities 

 and horizon.] Our specimen is probably from one or other of these places. 



Elceacrinus, sp. 



Remarks. The Collection contains a fragment of what must have been quite a large 



species of Elceacr'nius. It is an anal interradius, more than one and a quarter inches 



in length, and differs much in shape from the corresponding part both of E Verneuffi 



and of E. angularis. It is not, however, too large for the anal interradius in 



E. oboratus, Barris, and may possibly belong to that species. The lateral portions 



of the deltoid are cross-ridged in the usual way, and the plate is microscopically 



vermicular-striate. 



2f2 



