PALEONTOLOGY OF IOWA. 655 



same, 4 lines ; width of anal piece at base, 2^ lines ; ditto 

 at the top, \\ lines." 



This species occurs in the collections of the late Dr. TKOOST, under the name of 

 Doliolocrinites ovalis ; but the name is neither in the published catalogue or in the 

 MS. of the monograph. The specimen is from Sparta ( Tennessee), a locality which 

 has furnished other species of Warsaw limestone fossils. 



Fig. 12 a. Basal view of specimen. Fig. 12 b. Lateral view of the same. 



Geological formation and locality. In the Warsaw limestone : Spergen 

 hill, Indiana. 



Pentremites conoideus. 



PLATE XXII. FIG. 8, 9 & 10. 

 Pentremites conoideus : HALL, Transactions of the Albany Institute, Vol. iv, 1856. 



GENERAL form conoidal or pyramidal, with the angles 

 rounded : base subtruncate ; apex a little flattened. Basal 

 plates slightly convex : radial plates extremely elongated, 

 and deeply divided for the reception of the pseudoambu- 

 lacral areas ; interradial plates deeply inserted between 

 the radial plates, long lanceolate, and very acutely pointed 

 above. Pseudo-ambulacral spaces very elongate, narrow, 

 extending nearly to the base, with sides subparallel, convex 

 along the median line, which is sharply depressed. Poral 

 plates varying with age from twenty-five to fifty : ovarian 

 apertures circular : anal aperture ovate, and much larger 

 than the others. 



SURFACE marked by fine closely arranged striae, which, on 

 the radial plates, are parallel to the margins till near the 

 summit, where they are stronger and diverge from the 

 suture : striae on the interradial plates diverging from the 

 centre. Length, from one-fourth to three-fourths of an inch. 



In the young the base is more extended, and the poral pieces much fewer than 

 in older specimens. 



Fig. 8. A full-grown individual, which is more elongated than usual. 

 Fig. 9. A specimen of the ordinary form and size. 



Fig. 10. The base, showing form of basal plates and bases of the pseudoambulacral 

 areas. 



Geological formation and localities. In the horizon of the Warsaw lime- 

 stone : Spergen hill and Bloomington, Indiana. 



