SILTQTJAETA. 275 



8. Catopheagmtjs, Parietal valves BumerouSj irregulai-. 



Kg. 23. 



9. Balanfs. Parietal valves six ; opercular valves four, placed 



against each other conicaUy in pairs. This genus has 

 been divided into Acasta, Conoplea, Chirona, andBalanus. 

 Pig. 25, 26, 27. 



10. Ceeusia. Parietal valves, four supported on the edge of 



a funnel-shaped cavity. Pig. 28. 



11. PxEaoMA. Paries simple, supported on a cavity. This 



genus has been divided into the genera JSTobia, Savignium, 

 Pyrgoma, Adna, Megatrema, and Daracia. Pig. 29 to 33. 



SETIPEEOUS. Hairy. 



SHANK SHELL. The vulgar name for the shell designated 

 Murex Eapa. It is used in Ceylon for ornamental purposes. 



SIDEEOLITES. Montf A genus of microscopic Poraminifera. 



SIGAEETTJS. Lam. Fam. Macrostomata, Lam. — Bescr. Sub- 

 orbicular, oblique, haliotoid, thick ; spire depressed, consisting 

 of tv5^o or three rapidly increasing whorls ; aperture wide, entire, 

 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 genizs is distinguished 

 from Natica, by the width of the aperture, and the absence of 

 the umbihcal callosity. It may be known from Stomatia, and 

 Stomatella, by the texture, which in Sigaretus, is never pearly 

 as in Stomatia, the former being partly an internal shell. 

 Mostly brought from tropical climates. S. concavus. PL xv. 

 fig. 334. 



SILIQUA. Megerle. (A husk, or pod.) Legtjminabta, Schum. 

 A genus composed of species of Solen, Auct. which have an 

 internal rib- Pig. 51, Solen radiatus. 



SILIQUAEIA. (Lamarck, 1801.) Fam. Cricostomata, Bl. 

 Dorsalia, Lam. — Bescr. Tubular, rogose, spiral near the apex, 

 irregularly twisted near the aperture, with a longitudinal fissure 

 radiating from the apex, and proceeding through all the whorls 

 and sinuosities of the tube. — Ohs. This genus was included in 

 Serpula by Linnaeus, from which, however, it is distinguished 



T 2 



