276 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 25, 



5. Atrypa palmata, sp. n. PI. X. fig. 3. — Nearly hemispherical ; 



the ventral valve flat or slightly concave in the middle, with the 

 edges a little depressed, the dorsal valve highly convex ; valves 

 with 15 or 16 prominent rounded ribs, equal to the furrows 

 between them. Hinge line less than the width of the shell and 

 nearly straight. 

 Width f inch, length f of an inch. 



The equal rounding of the ribs and furrows gives a peculiar wavy 

 or palmate appearance to the surface of the shell, which is not of 

 common occurrence, but of which we have instances in the Atrypa 

 hemisphcBrica of our Caradoc sandstone, and in the Orthis callactis 

 of Dalman. The resemblance between our species and the A. he- 

 misphcBrica is very striking. 



6. Spirifer HAWKiNSii,5p.w. Pl.XI. fig.l. — Shell transversely elon- 



gated ; front rounded ; 5 imbricated ribs on each side, the two 

 middle ones acute, prominent, and nearly equal to the mesial 

 ridge, which is slightly furrowed ; the lateral ribs diminish in 

 importance as they approach the edge ; intervening furrows 

 rather wider than the ridges and rounded. Hinge area of the 

 width of the shell, broad and longitudinally striated. 



Cast of the dorsal valve ; beak prominent, with a deep mesial de- 

 pression, only 3 ribs distinctly marked on each side towards the 

 front of the shell ; rest of the east nearly smooth. 



The cast of this species bears great resemblance to that of aS'. spe- 

 ciosus from the Eifel. 



Width 2 inches, length nearly 1 inch. 



7. Spirifer Antarcticus, sp.n. PL XI. fig. 2. —Transversely fusi- 



form, nearly equivalved, with 20 to 24? prominent, sharp, im- 

 bricated ribs ; mesial ridge of the ventral valve similar in form 

 to the ribs, but larger and more elevated ; mesial furrow of the 

 dorsal valve deep and angular. Hinge area of the width of the 

 shell, very broad and triangular, with well-marked longitudinal 

 lines. 

 Cast ; ribs well-defined ; beak of the dorsal valve straight and very 

 prominent, with a deep mesial furrow and a slight furrow on 

 each side. 

 Width 3^ inches, length If inch ; height of hinge area f of an inch. 



8. Spirifer Orbignii, sp, n. PI. XI. fig. 3. — Gibbose, nearly semi- 



circular ; about 20 prominent, rounded, imbricated ribs ; mesial 

 ridge broad, elevated, flattened above and slightly furrowed ; 

 mesial furrow deep and rounded. Hinge area of the breadth 

 of the shell, narrow. 

 Cast ; ribs well-defined ; beak of the dorsal valve heart-shaped, with 

 a sharp deep mesial furrow and 2 or 5 nearly obsolete furrows 

 on each side ; ventral valve, cast of the mesial ridge traversed 

 for the upper half of its length by a sharp slit, which divides 

 the top of the ridge into two points. 

 Width 2\ inches, length 1^ inch. 



