SIMPLEGAS. 97 
SER’PULA. Lam. (A litle serpent.) Fam. Serpulacea, Lam. 
Deser. Tubular, narrow, pointed at the apex, gradually widen- 
ing towards the aperture, attached irregularly, sometimes spi- 
rally twisted, imbricated, keeled, or plain; aperture generally 
round, with the edge simple, or angulated by the termination of 
external ribs or keels. Obs. This description is intended to in- 
clude the genera Serpula, Spirorbis, Vermilia, and Galeolaria, 
&c. The Serpulze abound in all seas, on rocky shores at any 
time covered by water, attached to every kind of marinz sub- 
stance, whether moveable or stationary. ‘The fossil species occur 
in almost all strata. Fig. 4 to 7. 
SERPULA’CEA. Lam. The fourth family of the order of Se- 
dentary Annellides, containing the genera Spirorbis, Serpula, 
Vermilia, Galeolaria, Magilus. 
SESSILE CIRRI'PEDES. Lam. (Sessilis, low, dwarfish.) An 
order of Cirripedes, consisting of those which are attached by 
the base of the shells, containing the genera Tubicinella, Bala- 
nus, Coronula, Acasta, Pyrgoma, Creusia. To which may be 
added some other genera enumerated in explanation of figures 
14 to 33. 
SIDEROLITES. Lam. A genus of microscopic Foraminifera. 
SIGARE’TUS. Lam. Fam. Macrostomata, Lam. Deser. Sub- 
orbicular, oblique, haliotoid, thick; spire depressed, consisting 
of two or three rapidly increasing whorls; aperture wide, en- 
tire, modified by the last whorl, the width exceeding the length; 
columella tortuous; inner-lip spread thinly over part of the body 
whorl; epidermis thin. Obs. This genus is distinguished from 
Natica, by the width of the aperture and the want of the umbi- 
lical callosity. It may be known from Stomatia and Stomatella, 
by the texture, which, in Sigaretus, is never pearly as in Sto- 
matia. Sigaretus is partly an internal shell. Fig. 334, S. con- 
cavus. 7 
SI'LIQUA. Megerle. (A husk or pod.) Lzcuminaria, Schum. — 
A genus composed of species of Solen, Auct. which have an in- 
ternal rib. Fig. 61, Solen radiatus. 
SILIQUA’RIA. Brug. Fam. Cricostomata, Bl. Dorsalia, Lam. 
Deser. Tubular, rugose, spiral near the apex, irregularly twisted 
near the aperture, with a longitudinal fissure radiating from the 
apex, and proceeding through all the whorls and windings; 
aperture rounded. Obs. This genus may be known from Ser- 
pula, by the longitudinal slit. S. Muricata. Fig. 1, S. anguina. 
SIMPLE. (Simpler, Lat.) Single, entire, uninterrupted, un- 
divided. : 
SIM’PLEGAS. Bl. (Simplex, simple; yasrnp, gaster, belly.) A 
genus described as being discoidal, and having the spire un- 
covered like Ammonitzs, but having the chambers divided by 
simple septa, like Nautilus. Obs. The septa of the shell named 
fo) 
