SPIRIFER. 263 



SPILERULACEA. Lam. The fourth family of Cephalopoda, Lam. 

 described as multilocular, globular, sphserical, or oval, with the 

 whorls enveloping each other; some of them have a particular in- 

 ternal cavity, and are composed of a series of elongated, straight 

 and contiguous chambers which altogether form a covering for 

 the internal cavity. This family contains the genera Miliola, 

 Gyrogona and Melonia. 



SPH^RULITES. Lam. (Sphcera, a sphere) Fam. Rudistes, 

 Lam. and Bl. —Beacr. Orbicular, inequivalve, irregularly foliated 

 outside ; lower valve cup-shaped, depressed ; upper valve nearly 

 flat, like an operculum. — Ohs. These fossils are not regarded as 

 shells by all conchologists. S. foliacea, Fig. 193. 



SPHINCTERULUS. Montf. Lenticulina, Bl. A genus of micro- 

 scopic Foraminifera. 



SPINES. (Spina, a thorn.) Thin, pointed spikes. 



SPINOSE. (Spinosus.) Having spines or elevated points, as 

 Neritina spinosa. Fig. 325. 



SPIRAL. (Spira, a spire.) Revolving outwards from a central 

 apex or nucleus, like the spring of a watch. A shell or an 

 operculum, may be spiral, without being produced into a pyramid. 

 Bands of colour, striae, grooves, &c. commencing from the nucleus 

 and following the volutions of the shell, are described by the 

 above word. 



SPIRAMILLA. Bl. A genus of Serpulacea, differing from other 

 Serpulse principally in the characters of the animal. 



SPIRATELLA. Bl. Limacinea, Lam. Fig. 224. 



SPIRE. (Spira.) The cone or pyramid produced in a non- 

 symmetrical univalve by its oblique revolution downwards from 

 the apex or nucleus. The spire, in descriptions, includes all 

 the volutions above the aperture. See Introduction. 



SPIRIFER. Sow. (Spira, a spire ; fero, to bear.) Order, Bra- 

 chiopoda, Lam. — Descr. 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, 



