68 ORDOVIOIAN AXJ) SILURIAN BELLEROPHONTACEA. 



5. Cymbularia merita, sp. nov. Plate X, fig. 20. 



Specific Characters. — Shell involute, subglobose ; whorls rounded, slowly 

 expanding- to mouth, with high, strongly-arched dorsum, slightly excavated on 

 each side of narrow slightly-raised keel bearing flattened slit-band so as to form 

 parallel shallow revolving depressions. Umbilicus small or closed. Mouth sub- 

 triangular, large, about one and a-half times as wide as high, rather suddenly 

 expanded at base, the lower thickened margins being nearly at right angles to 

 vertical plane of shell; lateral margins making a dorsal angle of about 90°; dorsal 

 sinus V-shaped, large, wide, deep; lateral lobes prominent, angulated at corners of 

 sinus at about 60°. Surface of whorls marked by regular fine gently-arched 

 transverse lines, equidistant, rather closely placed, bending back sharply close to 

 keel to meet slit-band at about 30°, with traces of very delicate and closely-placed 

 faint revolving striae crossing them. 



Dimensions [Gr. 73904a]. — Height of shell to base of mouth, 12 mm.; height of 

 shell including mouth, 20 mm.; width of mouth at base, 20 mm.; diameter of 

 shell at umbilicus, 10 mm. 



Horizon. — AVenlock Shale. 



Locality. — Dudley. 



Remarks. — This species is bused on one specimen [0. 7 :> > ( .M»1- ti], in the British 

 Museum, which was labelled Bellerophm expansus, Sow. Only the apertural view 

 is seen, as the rest of the shell is imbedded in matrix, but the last whorl and the 

 mouth are well preserved and the ornament on the surface is clearly shown. In 

 the shape of the whorl, the narrow slightly-raised keel with a shallow revolving 

 depression on each side of it. and the course of the transverse lines on the shell, 

 it resembles I! fastigiatus, Lindstrom, 1 though the two species can scarcely be 

 considered identical. 



6. Cymbularia turnbulli, sp. nov. Plate XI, figs. 1 — 4-. 



? 1878. Bellrrojilitni ventriculatus, Edgell MS. Catal. Camb. Silur. Foss, Mus, Pract. Greol., i> ti?. 



Specific Characters. — Shell involute, subglobose, somewhal compressed, the 

 whorls subangular and higher than wide. Umbilicus small, deep, situated at less 

 than half height of shell. Outer whorl nearly completely enveloping inner 

 whorls, increasing in height rather rapidly, tectiform, subcarinate towards mouth ; 

 dorsum high, strongly-arched, subangular and weakly trilobed in outer third of 

 whorl by broad, faint, revolving depressions, the median portion being more 

 elevated and angulated towards mouth. Mouth widest at base with basal angles 

 projecting; inner lip somewhat reflexed ; lateral lips forming gently rounded lobes 



1 Lindstrom, op. cit., p. 76, pi. vi, tigs. 1 — 10. 



