SERPULA. 255 



families Dorsalia, Maldania, Serpulacea, andAmphitrites. Fig. 1 



to 13. 

 SEA DATE. The common name for Pholas Dactyls in the 



market, given to it on account of its cylindrical shape. Fig. 35. 

 SEGMENTINA. Flem. Nautilus Lacustris, Montagu. Test. 



Brit. Planorbis nitidus, Drap. tab. 2. Fig. 17 to 19. 

 SEMICORDATE. Half heart-shaped. 

 SEMIDISCOIDAL. Forming the half of a circular disc. 

 SEMILUNAR. Half moon- shaped. 

 SENECTUS. Humph. A genus of " Senectinse," thus described 



by Swainson : " Imperforate ; the base produced into a broad 



flat lobe, spire rather elevated and pointed ; the whorls convex ; 



aperture perfectly round ; not more oblique than Helix ; inner 



lip entirely wanting, imperialis. Mart. 180. f. 1790. marmoratus. 



1. M. 448. f. 1." Sw. p. 348. 

 SEMIPHYLLIDIANA. Lam. The second family of the order 



Gasteropoda, Lam. the genera of which are distinguished as 



follows : — 



1. Umbrella, round, flat ; apex central, muscular impression 



not interrupted. Fig. 233. 



2. Pleurobranchus, apex lateral, sub-spiral. Fig. 232. 

 SENOCLITA. Schum. Cineras, Leach. 



SEPTARIA. Lam. See Teredo. 



SEPTUM. (Lat.) An enclosure, applied to the thin plate of Cre- 

 pidula, fig. 239 ; also to the plates dividing the chambers of 

 multilocular shells. 



SERAPHS. Montf. Terebellum convolutum, Lam. Fig. 451. 



SERPULA. Auct. (A little serpent.) Fam. Surpulacea, Lam. 

 — Bescr. Tubular, narrow, pointed at the apex, gradually widen- 

 ing towards the aperture, attached irregularly, sometimes spirally, 

 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 include the 

 genera Serpula, Spirorbis, Vermilia, Galeolaria, &c. The 

 Serpulse abound in all seas, on rocky shores, at any time covered 



