OPHIOLEPIS. 151 



their surface is seen to be covered with fine granulations ; the dorsal and ventral 

 plates are small, rhomboidal, and much enveloped by the large lateral plates, these 

 carry on each side three or four stiff thornlike spines (PI. XIV, fig. 3, a, b) ; the 

 robust character of the ray, and the disposition of the spines, is well shown in these 

 figures. 



Affinities and Differences. — This species, in the general structure of the arms, 

 resembles OpMolepis Murravii, Forb. ; but it differs from that form in having them 

 rounder, less tapering, and more moniliform, in consequence of the thickness of the 

 scutal plates ; the short stiff spines of the lateral plates I have not seen on 0. Murravii. 



Locality and Stati^rapJdcal Position. — I have found this species on the surface of 

 slabs of Lower Lias limestone from Purton passage, near Berkeley, Gloucestershire, 

 associated with Pe?itacrinus tuberculatus. Miller, and young forms of Ammonites angulatus, 

 Schloth., and a small smooth Pecten, n. sp. My friend, the Rev. P. B. Brodie, P.G.S., 

 collected it from the same horizon at Down Hatherley in the Vale of Gloucester. To 

 his kindness I am indebted for the loan of the specimen figured in Plate XIV, fig, 3, a, 6. 



B. Species from the Middle Lias. 



Ophiolepis Murravii, Forbes, sp. PI. XIV, fig. 1, a, b, fig. 2 ; PI. XVII, fig. 2, a, b, 3, 4. 



PI. XIX, fig. 3. 



Ophixjba Murravii, Forbes. Proc. Geol. Soc, vol. iv, p. 233, fig. 1. Read Nov., 1843. 



— — Charlesworth. Lond. Geol. Journ., pi. xx, figs. 4, 5, 1847. 



— — Morris. Catalogue of British Fossils, 2nd ed., p. 84, 1854. 



— — Wright. Brit. Association Report for 1856, p. 403, 1857. 



— — Pictet. Paleontologie, 2nd ed., tome iv, p. 274, 1857. 

 Ophiolepis Murravii, Dujardin et Hupe. Hist. Nat. Echiuod., p. 245, 1862. 



Disk large in proportion to the arms ; dorsal surface covered with large scales ; 

 radial plates small, scutiform, and projecting on the disk; the converging ossicula 

 at their bases are comparatively large and broad ; arms relatively short and tapering. 

 Inferior ray-plates small and triangular. Lateral plates encroaching on those below, 

 and uniting with them beneath in the median line of the ray. They appear to have 

 supported large spines. 



Dimensions. — Diameter of the disk seven twentieths of an inch ; length of the rays 

 eight tenths of an inch. 



Description. — ^This beautiful little Ophiura is moderately large in proportion to the 



