100 SPIROGLYPHUS. 
sub-central; hinge with or without two or three rudimentary 
cardinal teeth; ligament prominent, placed upon thick callosi- 
ties; muscular impressions two, distant, rounded ; palleal impres- 
sion straight , with a deep sinus. Obs. Distinguished from the 
true Solenes by the central position of the umbones, and an in- 
ternal bar partly across the shell. S. radiata, fig. 61. 
SOLETEL'LINA. Bl. Saneurnonaria radiata, S. livida, S. Di- 
phos, Sow. and similar species. 
SPA’THA. Lea. A sub-genus of [npin#, composed of I. rubens 
and I. nilotica, which have not distinctly crenulated margins. 
S. solenoides, Mycetopus, D’Orb. Fig. 151. 
SPHAVNIA. Turt. A genus composed of a little shell resem- 
bling Saxicava in general appearance, but having a spoon-shaped 
process on the hinge of one valve. S. Binghamii, fig. 96. 
SPHAERULA’CEA. Bl. The first family of Cellulacea, consist- 
ing of the following genera of microscopic Foraminifera, viz. 
Miliola, Melonia, Saracenaria, Textularia. 
SPHASRULA’CEA. Lam. The fourth Family of Cephalopoda, 
Lam. Containing the genera Miliola, Gyrogona, Melonia. 
SPHA4ROIDI'NA. D’O1b. A genus of microscopic Foraminifera. 
SPHA/RULITES. Lam. (Sphera, a sphere.) Fam. Rudistes, 
Lam. and Bl. Deser. Orbicular, inequivalve, irregularly foliated 
outside; lower valve cup-shaped. depressed; upper valve nearly 
flat, like an operculum. Obs. These fossils are not regarded as 
shells by many conchologists. S. foliacea, fig. 193. 
SPINES. (Spina, a thorn.) Thin pointed spikes. 
SPINCTERULUS, Montf. Lenrticunina, Bl. A genus of mi- 
croscopic Foraminifeaa. 
SPIRAL. (Spira, aspire.) Revolving outwards from a central 
apex or nucleus, like the spring of a watch. A shell or an oper- 
culum may be spiral without being produced into a pyramid. 
SPIRATEL'LA. Bl. Limacina, Lam. fig. 224 
SPIRE. (Spira, a winding compass.) The cone or pyramid pro- 
duced in a non-symmetrical univalve, by its oblique revolution 
downwards from the nucleus or apex, The spire, in descrip- 
tion, includes all the volutions above the aperture. 
SPIRIFER. Sow. (Spira, a spire; fero, to bear.) Order. Brach- 
iopoda, Lam. Deser. Inequivalve, transverse, equilateral; hinge 
linear, straight, widely extended on both sides of the umbones, 
which are separated by a flat area in the upper and larger valve; 
this area is divided in the centre by a triangular pit, for the 
passage of the byssus; interior with two spirally convolute 
appendages. Obs. This genus, which is only known in a fossil 
State, is distinguished from Terebratula externally, by the flat 
area in one valve, internally, by the singular spiral process 
from which it derives its name. Fig. 214, 215. 
SPIRO’GLYPHUS. Dand. A genus consisting of a species of 
