150 Proceedings of Societies. 
Dunbar. The interest of this fact was a sufficient inducement to 
cause me at once to visit the locality where the star-fish was ob- 
tained, and where, by the kindness of Mr France, the proprietor of the 
brick-works, I succeeded in obtaining good specimens of the fossil. 
Notwithstanding some very marked characters, which might 
possibly be regarded as possessing higher than specific value, I pre- 
fer referring the star-fish of the Dunbar brick-clay to Miller and 
Troschel’s genus Ophiolepis, rather than encumbering the existing 
nomenclature with a new and doubtful generic name. The species, 
which is very distinct from every other described member of the 
genus, may be defined by the following diagnosis :— 
Ophiolepis gracilis (mihi), nov. spec. 
Upper surface of the disc covered with imbricated plates, a single 
circular plate occupying the centre, and with the radial shields 
large, and having their opposed edges in contact for their entire 
length. Dorsal shields of the arms about twice as broad as long 
near the disc, and thence with their breadth gradually decreasing 
in proportion to their length, until towards the distal extremity of 
the arm they become longer than broad; they cover the whole 
dorsal surface of the arm, and have their adoral and aboral margins 
transverse and parallel. Ventral shields of the arms very minute, 
and allowing the lateral shields of one side to meet those of the 
opposite side in the inferior median line of the arm. Aboral edge 
of each lateral shield with a notch for the exit of a cirrus. Spines 
about once and a-half as long as the breadth of the arms. Arms 
about five times as long as the diameter of the disc, and gradually 
tapering to a fine point. 
The size of the largest specimens obtained is about four inches 
from tip to tip of the arms. 
Fossil in brick-clay of the Post-pliocene age, near Dunbar, Scot- 
land. 
One of the most remarkable features in the present species is the 
rudimental condition of the ventral shields of the arms; these 
shields being much smaller than in Ophiolepis ciliata (Mil. and 
Trosch.), where they are exceptionally small among the Ophiuride, 
- and where the lateral shields bear only short papilliform spines 
instead of the long, highly-developed spines of O. gracilis. It was 
only after having sought in vain for the ventral shields in some 
dozens of specimens that I succeeded in detecting them in a single 
instance. In this case they appeared in a view of the internal sur- 
face of the ventral wall (fig. B) as very minute rhombic plates 
lying along the mesial line, where they were interposed between 
the angles of the lateral shields. It is quite possible that the 
ventral plates are more fully displayed upon the outer surface of 
the wall, but in no case did I find this surface sufficiently exposed 
to enable me to obtain a view of them; while the inner surface, 
on the contrary, was frequently well exposed by the disappearance 
in the fossil of the dorsal shields, and of the series of vertebra-like 
ossicles, which, in the living Ophiuride, occupies the axis of the 
