as SOLARIUM. 
Simplegas, by De Montfort, are evidently sinuous, according te 
his figure. Fig. 475, S. sulcata. 
SINISTRAL. (Sinister, left.) On the left side. A sinistral shell 
is a reversed one. ‘The sinistral valve of a bivalve shell, may be 
known by placing the shell with its hgamentary or posterior 
part towards the observer; the sides of the shell will then cor- 
respond with his right and left sides. 
SINUS. Sinvosiry. (Sinus, Lat. a winding or bay.) A winding, 
or tortuous excavation. The sinus in the outer-lip of Strom- 
bus, fig. 406; and that in the muscular impression of Venus, 
fig. 119, will be indicated by the letter s. 
SIPHON. (S:idor, siphon.) A pipe or tube. A shelly tube passing 
through the septa of chambered shells. Ez. Spirula, fig. 471, 
and all the Ammonacea. 
SIPHONA’RIA. Sow. (Sidor, siphon.) Fam. Phillidiana, Lam. 
Patelloidea, Bl. Deser. Patelliform, depressed, inclining to oval, 
ribbed; apex nearly central, obliquely inclining towards the pos- 
terlor margin; muscular impression partly encircling the central 
disc, but interrupted in front where the head of the animal re- 
poses, and at the side, by a siphon or canal passing from the 
apex tothe margin. Obs. This siphon, which in some species 
is very distinct, serves to distinguish this genus from Patella. 
S. sipho, fig. 231.* 
SIPHONOBRANCHIA'TA. Bl. (Siphon and Branchie, gills.) 
The first order of Paracephalophora Dioica, Bl. Divided into 
the families Siphonostomata, Entomostomata, and Angyosto- 
mata. 
SIPHONOSTOM ATA. Bl. Sidov, siphon; cropa, stoma, mouth.) 
The first family of Siphonobranchiata, Bl. containing the ge- 
nera Pleurotoma, Rostellaria, Fusus, Pyrula, Fasciolaria, Turbi- 
nellus, Columbella, Triton, Murex, Ranella. 
SIS’TRUM. Montf. Rictnuna, Auct. - 
SKE’NEA. Flem. A genus including some species of Euomphalus 
and Cirrus, Sow. 
SMI’LIUM. Leach. Fam. Pedunculated Cirripedes. Descr. Thir- 
teen pieces, ten of which are in pairs, lateral, subtriangular ; 
two anterior. dorsal and ventral incurved, triangular; one pos- 
terior dorsal, linear; all smooth; pedicle hairy. Obs. This 
genus is distinguished from Pentelasmis by the number of its 
valves, and from Scalpellum, by the hairy pedicle. 5, Peronii, 
fig. 36. 
SOLARIUM. Auct. (A terrace or gallery.) Fam. Turbinacea, 
Lam. Goniostomata, BI. Deser. Piscoidal beneath, conical 
above, with a wide umbilicus, the spiral margin of which is an- 
gulated and crenulated; aperture trapezoidal, peritréme thin, 
sharp; columella straight; operculum horny, sub-spiral. Obs. 
The Solarium Perspectivum, is commonly called the Staircase 
