fAnK] HEMIASTI-:R STELLA. 85 



Morton in this regard, but the examination of a lariiiM- iinionnt of mate- 

 rial shows tliat the new species, H. inerassatus^ there described is oiiJy a 

 large form of //. stvlla, so that it becomes necessary to discard the former 

 tei-m and employ both Jf. Stella and H. parastatufi of Morton . Rem iastvr 

 Wethcrhyi de Loriol is a.])parently identical with //. Htdla Morton. 



The test is small, oval, aiut cordate, and much elevated on the pos- 

 terior portion of the ni)per surface. The whole test has a rounded, 

 full outline, that is much increased by the absence of the usually deep 

 iintcrior groove, which \\\ Jl. utella docs not reach thenuirgiu (PI. XLVi, 

 I'Mg. Irt). The posterior border is tiatly and nearly vertically truncated. 



The ambnlacral areas are deju-essed in tlic petaloidal ]»ortioTis which, 

 in the antero-lateriil pair, are twice as long as in the ]»ost(^rol:iteiiil. 

 The poril'erous zones are narrow; the pores have transverse slit-like 

 o[>enings. The un[)aired ambulacrum is situated in the anterior groove. 



The surface of the test is covered with innumerable small tubercles, 

 between which is a microscoiuc graiudation. The ]>eripetalous fasciole 

 is very distinct, oval, and passes with a regular curve about the ends 

 of the i>etaloidal areas. The surface of the test is covered with minute 

 tubercles, between which are microscopic grannies. Tlu^ apical disk 

 is small, and situated posteriorly to the center of the U])per surface ot 

 the test. 



The mouth opening is transversely oval, bilabiate, and placed near 

 the anterior margin. The anal opening is small, oval, and situated at 

 the upper part of the truncated i^osterior margin. 



Related forms. — Hemiaster stella is unique among American Hemias- 

 ters. The shallow anterior grcmve, that falls short of the margin, and 

 the full elevated test readily distinguish it from other forms. 



Locality and (jeologlcal horizon. — Hemiaster stella is found in the yel- 

 low limestone of the middle marl bed (upper Cretaceous) of Timber 

 creek, ISTew Jersey. 



Collections. — U. !S. JSTaticmal Museum; Philadelphia Academy of Nat- 

 ural Sciences; Johns Hopkins University. 



Hemiaster itngula (Morton). 

 Plate XLVI, Figs. 2a-g. 



Sjyatangns HV. Morton, 1830. Am. Jonr. Sci., 1st. scr., vol. 17, p. 28G. 



Sjyatanyns loujnla Morton, 1833. Aiut .lonr. Sci., l.stser., voL 23, p. 131, PI. 10, Fig. G. 



Spalanyns uiufula Morton, 1831. Synop. Organ. Ediiiains, Cretaceous, p. 78, PI. 10, 



Fig. 6. 

 Micraster ungnJa Agassiz and Desor, 1847. Cat. rais., p. 111. 

 Spatangus ungula Broun, 1818. Inrtex Pal., vol. 1, p. IIGI. 

 Holaster ungula Grabb, 1859. Cat. Invert. Fossils, Cretaceous, p. 19. 

 Hemiaster angula Clark, 1891. Johns Hopkins University Circulars, No. 87, p. 77. 



Determinative characters. — Test oval, cordiforin, elevated; upper sur- 

 face inflated, elevated posteriorly; lower surface flat; sides sU)ping; 

 anterior sulcus narrow and deep. Ambulacra narrow ; poriferous zones 

 sti'aight, depressed, petaloidal. Peripetalous fasciole deeply bent 



