OPHIOLEPIS. 



161 



to their terminal end. They were stoutly built of rings of imbricated scales, which are 

 neatly arranged so as to form a chain-like structure (fig. 3 a), each upper segment 

 being made up of two halves united along the middle line, as shown in fig. 3 h. The 

 under segment is formed likewise of two pear-shaped, obliquely-twisted scales, which at 

 their junction in the mesial line have a small supplementary scale inserted between the 

 round terminations of the lateral pieces. The rays appear to have been much flexed, as 

 all the arms are bent (fig. 3 a) in different directions in the smaller specimen on a slab 

 of Grey Limestone now before me. 



Affinities and Differences. — OpMolepls Leclcenhyi, Wr., differs much from Opidolepis 

 Murravii, Wr. The disk is smaller, and the arms longer and more slender, and thus 

 this species is easily distinguished from the Lias forms. 



Locality and StratigrapJiical Position. — The two specimens of this Brittle-star were 

 collected from the Grey Limestone near Scarborough, which represents the middle zone 

 {Stephanoceras Humphriesianuni) of the Inferior Oofite. These little radiates appear to 

 be rare, as I have seen no other examples of them in any other local collection. 



B. Species from the Tipper Triassic. 



Ophiolepis Damesii. Wriglit, n. sp. PL XXI, figs. 4 and 5. 



Ophiolepis Damesii, Wright. Zeitschrift der Deutschen geologisclien Gesellscbaft, 



pi. xxix, figs. 5 a, b, p. 821, Jahrgang 1874. 



Body-disk small, upper surface convex and undulated, rays long, cylindrical, 

 four times the length of the diameter of the disk ; dorsal shields of rays smooth, 

 semicircular ; ventral shields form a double chain of round prominent joints, which 

 extend from the mouth-opening to the end of the rays. 



Dimensions. — Diameter of the disk one quarter of an inch. Length of the rays one 

 inch. 



Description. — This beautiful little Brittle-Star belongs to the genus OpiUolepjis . The 

 upper surface of the discal body is convex and undulated, being elevated at the points in 

 the circumference where the rays proceed outwards, and depressed and concave between 

 the inter-radial elevations. The round slender rays end in very fine points. The upper 

 surface of the discal body is covered with small delicate scales. The rays have semi- 

 circular shields on their upper surface, and on the under side a double row of articulated 

 segments, which extend from the mouth to the end of the rays. 



This Ophiolepis resembles Ophiolepis Murravii^ Porbes, from the Marlstone of York- 



