LLARK] OPHIOGLYPHA BKIDGERENSIS. 29 



Cretaceous, there is little ,'uiioii^- the American forms with which it 

 may be compared, especially as the two Jurassic types previously 

 described show marked diftereuces in every particular. 



Local it 1/ and (frologicai horizon. — The specimens de.scribed by Gabb 

 and examined by the writer are from the yellow liniestone of Vin- 

 ceutown, New Jersey. The yellow limestone belongs to the middle 

 marl bed and is upper Cretaceous. 



Collections. Philadelphia Academy of Natural Sciences; Johns 

 Hopkins University. 



ASTEROIDEA. 

 OPHIURIB^^i:. 



Body star-shaped, with central disk and elongated arms, which are 

 distinctly separated from the disk. The ambulacra! grooves are gen- 

 erally covered with plates. 



OPHIOGLYPHA Lyman. 



Ophioglypha bridgerensis (Meek). 



Plate IV, Figs. 2a-h. 



Ophioderma f bridgerensis Meek, 1873. U. 8. Geol. Surv. Territories for 1872, p. 475. 

 Ophioderma ? bridgerensis White, 1883. U. S. Geol. and Geog. Surv. of the Terri- 

 tories for 1878, pp. 8, 9, PI. 12, Fig. 12a. 



Determinative characters. — Disk composed of numerous small imbri- 

 cating plates. Upper arm plates wider than long, the outer angles 

 sharp and extending between the side arm plates, which are slightly 

 smaller. Under arm plates long and nearly rectangular in shape. 



Dimensions. — Diameter of disk, J inch. Length of arm, f inch. 

 Width of arm near disk, ./jj inch. 



Description. — The single specimen of this species thus far found is 

 described in a foot-note to a list of specimens appended to the pale- 

 ontological report of F. B, Meek in the Annual Eeport of the U. S. 

 Geological Survey of the Territories for 1872, and redescribed and 

 figured by Dr. C. A. White in the Annual Report for 1878 of the same 

 organization. This specimen, which has been carefully examined by the 

 writer, presents the upper surface of the disk and fragments of the five 

 arms. LTpon all but one fragment the upper and side arm plates are 

 shown, while upon that a minute i)ortion of the under surface of a single 

 arm with the under arm plates and ambulacral openings is preserved. 



The disk is described by Meek as "depressed, nearly circular, show- 

 ing on the dorsal side ten ovate- sub trigonal radial plates, that are joined 

 together o\'er the inner ends of the arms, so as to form five i^airs." A 

 close examination of the specimen shows that the disk is made up of 

 numerous small imbricating plates, and that the sui)posed division into 



