194 BRITISH PALAZOZOIC FOSSILS. [Bracuioropa. 
area broad, curved, triangular, height one-third of its width, foramen narrow, with prominent edges ; receiving 
valye with a very deep, wide, rounded, mesial sulcus; and four or five strong, rounded cost:e on each side ; 
receiving valve moderately convex, with a corresponding prominent, rounded mesial ridge and set of costz ; 
entire surface covered with close, fine, subequal costze (seven in one line), at three lines from the beak. 
80 
Average width one inch one line, proportional length of receiving valve about =. 
This species seems to me totally distinct (when typical forms are considered) from the Spirifer radiatus 
of Sowerby, by its very strongly costated valves, and for the same reason it agrees perfectly with Dalman’s 
Delthyris cyrtena, which has usually been referred to the S. radiatus of Sowerby, although it is his S. inter- 
lineatus which presents the mixed costated and lineated character of Dalman’s species; the S. interlineatus of 
the Silurian System has more obtuse lateral angles than Dalman’s specimens ; but this character seems to vary. 
Position and Locality—Not uncommon in the Wenlock limestone of Ledbury, Herefordshire ; rare in 
the Wenlock limestone of Woolhope. 
SPIRIFERA INSULARIS (Eichw. Sp.) 
Ref. = Terebratula insularis Eichw. Urwelt. Russl. Part II. t. 2. f. 6. Spirifer id. M. V.K. Geol. Russ. t. 8. f. 7. 
Sp. Oh.—Suborbicular, very gibbous; entering valve sometimes very slightly longer than the receiving one 
from its larger, much arched, tumid beak, very gibbous, nearly three times the depth of the receiving valve, 
with a broad, elevated, flattened mesial ridge, with narrow, nearly vertical sides, extending from the very 
deep oblong sinus in the front margin, to within a short variable distance of the beak; sides tumid ; lateral 
margins rounded, advancing with a deep wave towards the receiving valve, before turning angularly upwards to 
form the marginal sinus ; receiving valve tumid for a short distance near the small short beak, which is not 
incurved; sides flattened or slightly concaye towards the margin, middle portion abruptly depressed into a 
wide, flattened, angular depression, corresponding with the sinus in the front margin; hinge-line consider- 
ably less than the width of the shell, cardinal angles obtuse ; cardinal area of receiving valve flat and 
triangular, about five times wider than high, inclined backwards at an angle of 105°; cardinal area of 
entering valve very narrow, invisible externally, from being inflected parallel with the plane of the lateral 
margins, with its small triangular open foramen. Internally the entering valve shews a slender mesial septum, 
extending one half the length of the shell, but scarcely raised above the surface of the valve ; and on each 
side of the little triangular opening beneath the beak is a large divergent cardinal tooth (broken at the 
apex); the receiving valve shews a similar mesial septum, and two moderately long dental lamelle, diverging 
at an angle of about 80°; surface smooth. Length one inch one line, proportional width ;%, depth of 
entering valve at middle, and height of sinus, ;;,, depth of receiving valve ;;,. 
The discovery, on a small fragment, of the concealed cardinal area of the entering valve with its small 
triangular foramen, proves the correctness of M. de Verneuil’s reference of this fossil to the genus Spi- 
rifera, and the great divergent cardinal teeth, though broken at the apex in the only specimen shewing these 
parts, present the usual appearance of the bases of the spiral appendages of Spiri/era. 
Position and Locality—Common in the Coniston or Bala limestone of Coniston, Lancashire ; rare in 
the impure schistose limestone of Llangynyw, Montgomeryshire. 
SPIRIFERA PER-CRASSA (J/‘°Coy). 
Ref. and Syn.= Atrypa crassa Sow. Sil. Syst. t. 21. f. 1. 
Sp. Ch.—Transversely oval, or subrhomboidal, gibbous ; large valve with a mesial coneayity, narrow and 
ill defined towards the beak, very wide and bounded by two obtuse ridges towards the front; sides sloping 
rapidly; beak prominent, apical angle about 115° (less when young, rather more when old), sides rounded, 
front slightly produced in an obtusely rounded deflected lobe: lateral margins nearly level; small valve tumid, 
with an obtuse, tongue-shaped lobe in the front; slightly elevated corresponding flattened ridge not extending 
half way to the beak : casfs of receiving valve shew two very strong slits of the dental lamelle, converging 
