150 



LIASSIC OPHIURIDtE. 



Genus — Ophiolepis, Muller and Troschel, 1842. 



The upper surface of the disk provided with naked scales or shields (PI. XIII, fig. 2) ; 

 two genital slits on each side of the interbrachial spaces close to the arms ; oral fissures 

 bordered with a single row of hard papillae ; maxillge armed with simple prominent 

 dental processes (fig. 2) ; the lateral scutse of the arms support papillae or spines ; one or 

 two scales on each tentacule pore ; the oral plates are simple and heart-shaped. 



The genus Ophiolepis forms a natural group, composed of many species, which have 

 been arranged by Miiller and Troschel into three sections. The first includes those in 

 which the radial or dorsal plates on the disk are surrounded with a circle of smaller 

 scales ; the second in which the small scales are absent ; and third those which, besides 

 scales, have rows of spines on the dorsal surface. 



* Species in which the dorsal plates of the disk are surrounded with small scales. 

 Type, O. ANNULOSA, PI. XIII, fig. 2. 



** Species in which the dorsal plates are not surrounded hy scales. Type, 



O. CILIATA, PI. XIII, fig. 3. 



*** Species in ivhich the disk, besides scales, supports roios of spines. Type, 

 0. scoLOPENDRiCA, Linck, tab. xl, fig. 71, 72. 



The third section corresponds to the genus Ophiopholis, M. and T., into which the 

 species are now merged. 



A. Species of the Lower Lias. 

 Ophiolepis Ramsayi, Wright, n. sp. PI. XIV, fig. 3, a, h. 



Disk small ; rays short, robust cylindrical ; surface of all the scuta covered with fine 

 granulations ; the lateral scuta armed with short, stout, thornlike spines. 



Dimensions. — Length of the rays eleven twentieths of an inch. 



Description. — This beautiful little Brittle-star is sometimes found on the surface of 

 slabs of Lower Lias, associated with portions of the stem of Pentacrinus tuber culatus. 

 Mill. The disk appears to have been small ; the arms are short, stout, cylindrical, and 

 clothed with a firm armour of prominent plates ; examined with an inch-object-glass. 



