94 SAXICAVA. 
RUDIS'TES. Bl. A family of the order Conchifera Monomyaria, 
Lam. containing the genera Spheerulites, Radiolites, Birostrites, 
Caleeola, Discina, Crania. 
RUDIS'TES. Lam. The second order of the class Acephalo- 
phora, Bl. containing the genera Spheerulites, Crania, Hippu- 
rites, Radiolites, Birostrites and Calceola. 
RUDOL’'PHUS. Schum. Monoceros, Auct. 
RUPELLA’RIA. Fl. de Belvue. An unfigured shell, placed by 
de Blainville in a division of the genus Venerirupis. 
RU’PICOLA. Fl. de Belvue. Described by De Blainville as an 
equivalve, terebrating species of Anavina. A. rupicola, Lam. 
SA’GITTA. (An arrow.) Ancient name for Belemnites. 
SALPA’CEA. Bl. The second family of the order Heterobran- 
chiata, Bl. containing no genera of shells. 
SANDALIN’A. Schum. Crepipunina, Lam. A genus of micros- 
copic Foraminifera. 
SANGUINOLA'RIA. Lam. (Sanguis, blood.) Fam. Nymphacea, 
Lam. Pyloridea, Bl. Deser. Equivalve, imequilateral, trans. 
verse, sub-ovate, rounded anteriorly, subrostrate posteriorly, 
compressed, thin, covered with a shining epidermis, gaping at 
the sides; hinge with two cardinal teeth in each valve, and an 
external ligament supported upon a prominent fulcrum; mus- 
cular impressions, two in each valve, lateral, irregular; palleal 
impression with a large sinus. Obs. This description is made 
to exclude some of Lamarck’s species of Sanguinolaria, such as 
S. occidens, and S. rugosa, which are Psammobie; and to in- 
clude others which he has left out. The Sanguinolariz are 
sub-rostrated posteriorly, while the Psammobiz are sub-qua- 
drate and have a posterior angle. Fig. 98, S. rosea. 
SARACENA/RIA. Defr. A genus of microscopic Foraminifera. 
SAVIG’NIUM. Leach. A genus of Sessile Cirripedes, described 
as composed of four valves soldered together, and a convex bi- 
valve operculum; the ventral and posterior valve on each side 
being soldered together, in other respects resembling Pyreoma. 
Fig. 30. 
SAXICA'VA. Auct. (Sarum, a stone; cava, a hollow.) Fam. 
Lithophagi, Lam. Pyloridea, Bl. Descr. Transverse, irregular, 
generally oblong, inequilateral, sub-equivalve, gaping anteriorly ; 
ligament external; muscular impressions two, lateral; palleal 
impression interrupted, not sinuated; hinge, when young, with 
sometimes two or three minute, obtuse, generally indistinct car- 
dinal teeth, which become obsolete when full grown. Obs. 
Several genera have been founded only upon the difference be- 
tween the young and old shell of the same species of this genus. 
The Saxicavee are found in the little hollows of rocks, in cavi- 
ties on the backs of oysters, of roots of sea weeds, &c. S. ru- 
gosa, Fig. 94. 
