140 LIASSIC OPHIURIDiE. 



DESCRIPTION OF THE FOSSIL SPECIES. 



Genus Ophioderma, Muller and Troschel, 1842. 



The disk covered with small, close-set granulations ; arms long, smooth", and slender ; 

 the lateral borders provided with short papillae or spines closely applied to the lateral 

 plates. Four genital slits in each interbrachial space, disposed in pairs behind each 

 other; two are situated behind the buccal plates, from whence they diverge outwards, and 

 two are placed near the border of the disk. The slits always lie behind each other in the 

 same radial line. The buccal fissures are furnished with small strong papillae. PI. XIII, 

 fig. 1, is the disk and rays of Ophioderma longicauda, Linck, which exhibit very satis- 

 factorily the organic characters of this group. 



The genus Ophioderma was established by Miiller and Troschel for certain species 

 of Ophiura which had for their type the Stella lumhricalis longicauda, Linck, tab. xi, 

 No. 17 = 0])hiura lacertosa, Lamarck. 



The Ophiodermas are remarkable for possessing a very smooth body and arms, 

 the granulations and spines are so fine and regular that the rays reseuible the skin of 

 an Ophidian reptile, hence the specific name given by Lamarck to Linck's type. Of the 

 fourteen living species, one is found in the Mediterranean and the others in the warmer 

 seas of the globe. The fossil species have, at the present time, been found only in the 

 Lias formation. 



Ophioderma Milleri, Phillips, sp. PI. XVI, figs. 2, 3, a, b, 4. 



AsTERiAS SPH^RULATA, Young and Bird. Geological Survey of the Yorkshire Coast, 



pi. V, fig. 6, 1822. 

 Ophiura Milleri, Phillips. Geol. of Yorkshire, pi. xiii, fig. 20, p. 169, 1829. 



— Milleri, Charlesworth. London Geological Journal, pi. viii, 1847. 

 Ophiurella Milleri, Agassiz. Mem. Sc. Nat. Neuchatel, p. 192, 1836. 

 Ophioderma Milleri, Wright. Ann. and Mag. of Nat. Hist., 2nd series, vol. xiii, 1854. 



— Milleri, Forbes. Morris, Cat. British Fossils, 2nd ed., p. 84, 1854. 



— Milleri, Wi-ight. Brit. Association Report for 1856, p. 402, 1857. 

 Pal^ocoma Milleri, d'Orbigny. Prodrome de Paleontologie, tome i, p. 240, 1850. 



— Milleri, Oppel. Der Juraforniation, p. 190, 1856. 



— Milleri, Bujardin et Hupe. Hist. Nat. des Zoophytes Echinodermes, 



p. 294, 1862. 



Disk flat, circular, with ten radial plates, nearly equidistant around the margin ; a 

 short series of transverse plates extending between each pair towards the centre of the 

 disk ; arms long, round, smooth, tapering from the base to the apex ; spines very small, 

 and closely applied to the lateral plates. 



