SPIRIFERIDA. 321 
cyrTIA, Dalman, 1828. Shell impunctate, pyramidal, beak 
prominent, area equiangular, deltidium with a small tubular 
foramen. Fossil,10sp. Silurian—Trias; Europe. S. trapezoid- 
alis, Dalman (cxxxvii, 3°. 
MARTINIA, M’Coy, 1844. (Amboceelia, Hall, 1860.) Dorsal 
margin shorter than the width of the shell, the angles of the 
hinge-margin shortly rounded ; surface smooth ; spiral lamellee 
small. Silur. —Carb.; Eur. nit SPs. glaber, Sowb. 
SUESSIA, Deslongchamps, 1855. (Dedicated to M. Suess.) 
Shell like Spirifer; texture fibrous; hinge-area wide as the 
shell; foramen deltoid ; large valve with two cardinal septa, and 
& prominent central septum, supporting a little plate; small 
valve with a trilobed cardinal process, and a broad four-partite 
hinge-plate, with processes from the outer angles of the dental 
sockets; crura of the spires united by a transverse band sup- 
porting a small process. Fossil,2sp. Upper Lias; Normandy. 
S. imbricata, Desl. (exxxvii, 1,2). 
SYRINGOTHYRIS, Winchell, 1863. Shell like that of Spirifer, 
with an elongated hinge-line. Ventral valve with a broad mesial 
sinus, a very broad area, and a narrow triangular fissure closed 
towards the apex by an external convex pseudo-deltidium ; 
beneath which, and diverging from it, is another transverse plate 
connecting the vertical dental lamellz, which are incurved so as 
to nearly join their inferior edges, thus forming a fissured tube, 
which projects beyond the limits of the plate from which it 
originates into the interior of the shell. A low median ridge 
extends from the beak to the anterior part of the valve. Dorsal 
valve depressed, without an area,and with a distinct mesial fold. 
Shell-structure punctate. Fossil, 2 sp. Carboniferous; United 
States, Ireland, Belgium. 8S. typa, Winchell (cxxxvii, 6). ‘Is 
it not an abnormal Spirifer or Cyrtia ?”—MEEK. 
oyrTINA, Davidson, 1858. (Htym.—Modified from the diminu- 
tive [ Cyr tidium | of Cyrtia.) Shell resembling Spirifer, but 
without the vertical shelly plates which diverge from the 
extremity of the beak. Interior of ventral valve with two con- 
tiguous vertical septa, which coalesce into one median plate, 
which extends from the extremity of the beak to within a short 
distance of the frontal margin, and then diverges to form dental 
plates, as in Pentamerus. The fissure is covered by an arch- 
shaped deltidium; but in C. Demarlii the median septum is 
continued as far as the under surface of the deltidium, and the 
dental plates are fixed to the sides, instead of the upper edge, as 
in C. heteroclita and C. septosa. “ Spiral coils having the same 
position as in Spirifer, but the first two coils are connected a 
little in front of the mid-length by an apparatus somewhat like 
that of Spirigera, but not so complicated. A very slender process 
springs upwards towards the central valve from each coil, and, 
