98 MESOZOIC AND CENOZOIC ECHINODEKMATA OP THE UNITED STATES. 



Description. — This species is represented by numerous flattened casts, none of which show- 

 clearly the original form of the test, although it is apparently somewhat flatter than the other 

 New Jersey Cretaceous Hemiasters. The test is relatively large. It is but slightly elevated 

 with a somewhat flattened upper surface. 



The ambulacra are pronounced, with weakly depressed petaloidal areas. The unpaired, 

 posterior interambulacrum is nearly flat with a low truncated posterior surface. The petals of 

 the posterolateral pair are relatively long and narrow and less than twice the length of the 

 anterolateral pair. The unpaired ambulacrum is not deeply depressed and does not form a 

 pronounced sulcus on the anterior margin. The apical' system is small but not as strongly 

 excentric as in some of the other Cretaceous species. The peristome has a distinct overhanging 

 lip. The peripetalous fascioles can not be seen. 



Belated forms. — This species is related to both H. parastatus and H. welleri. From the 

 former it is separated by its shallower and narrower ambulacral petals and less elevated form; 

 from the latter by its longer and narrower posterolateral ambulacral petals and flatter form. 



Locality. — Lorillard clay pits near Keyport, N. J. 



Geologic horizon. — Woodbury clay of Matawan group, Upper Cretaceous. 



Collections. — Geological Survey of New Jersey; Johns Hopkins University. 



Hemiaster welleri Clark. 

 Plate LII, figures 2a-c. 



Hemiaster welleri Clark, 1907, in Weller, Cretaceous paleontology of New Jersey: Geol. Survey New Jersey, pp. 302- 

 303, PL XVII, figs. 4-6. 



Determinative characters. — Test cordiform, inflated; upper surface only slightly elevated 

 posteriorly; lower surface flat; sides rounded. Ambulacra depressed. Apical system small. 

 Peristome with distinct overhanging Up. Periproct small, high on posterior truncated surface. 



Dimensions. — Length 27 millimeters; width 24 millimeters; height 17 millimeters. 



Description. — This species has afforded few specimens, and those for the most part casts, but 

 it is evidently distinct from the other forms described. The test is moderately high, clearly cor- 

 diform, and with depressed ambulacra. The anterior sulcus is broad and clearly defined but does 

 not deeply indent the anterior ambitus. The posterior ridge is not greatly accentuated and ter- 

 minates in a well-defined, truncated posterior surface. The sides are rounded. The lower sur- 

 face is slightly inflated. 



The ambulacra are moderately depressed in their petaloidal portions, the posterolateral pair 

 being considerably shorter than the anterolateral, although the difference is less marked in this 

 species than in the other New Jersey Cretaceous Hemiasters. The anterior ambulacrum is in a 

 broad shallow groove that largely disappears before the ambitus is reached. 



The apical system is small and imperfectly shown on the casts from which its characters can 

 be alone obtained. 



The peristome is of moderate size with distinct overhanging lip. The periproct is small and 

 situated high on the truncated posterior surface. 



Belated forms. — Hemiaster welleri is related to H. parastatus from which, however, it is sepa- 

 rated by its less deeply depressed ambulacral furrows and less elevated upper surface. It also 

 shows points of resemblance to H. Jcummeli from which, however, it is separated by its lower 

 posterolateral ambulacral petals and less elevated posterior ridge on the upper surface. 



Localities. — Railroad cut 1 mile south of Lower Jamesburg (type) ; 3 miles east of James- 

 burg; Reeves clay pit; Lenola; bluff east of Atlantic Highlands, N. J. 



Geologic horizon. — Merchantville clay of Matawan group and Navesink marl of Monmouth 

 group, Upper Cretaceous. 



Collections. — Geological Survey of New Jersey; Johns Hopkins University. 



