Fig. 3, 
Fig. 4 
fig. 6 
Fig. 6 
Jurassic Fauna from Central Arabia. 403 
coste and the widely convex lobe-like rib in front separated 
by a broad and deep furrow. 
Internal surface of a similar valve, but belonging to another 
individual, showing a wide ligament area and the reniform 
muscular scar. 
Lopha solitaria (J. de C. Sowerby). ~ 
. A young form of this species showing a narrow oblong summit- 
region, a widened base, and a series of deeply angulate diver- 
gent ribs. 
. Front margin of the same specimen, showing the prominent 
angulations, which receive the interlocking parts of the 
opposing valve. 
Exogyra bruntrutana (Thurmann, P, de Loriol). 
. Valve-interiors embedded in matrix. 
Chlamys articulatus (Schlotheim). 
Fig. 7. External view of a fragmentary valve, showing the lamellated 
character of the costz. 
Hinnites cf. inequistriatus (Voltz), Thurmann. 
Fig. 8, Representing part of an upper valve taken from a plasticine cast 
of a natural cavity in matrix, showing strong distant costz 
and intermediate subsidiary ribbing. 
Terebratula subsella, Leymerie. 
tg. 9. Showing a large foramen lying close to the umbone of the dorsal 
valve, and the biplicated base. 
Ig. 10, Different view of the same specimen, exhibiting the biplicated 
base of the dorsal valve, placed uppermost in the figure. 
Rhynchonella sp. 
Fig. 11. Shows dorsal valve chiefly, the other being hidden in matrix 
with the exception of the narrow lateral surface of the beak. 
Numerous ribs are present. 
Stomatopora cf. waltoni, Haime. 
Fig. 12. Showing dichotomizing branches and minute equidistant aper- 
tures. X 3. 
Rhabdocidaris sp. 
fig. 13. Showing the trilateral form of this spine, with its marginal 
/ote.—Figures of the natural size, with the exception of fig. 12 
dentations, the median ridge, and the minutely beaded surface. 
. - "ye . 2 
which is magnified three diameters. 
