454 MOLLUSCA. TEREDINADiE. Teredo 



Gen. CYRENA. — Suborbicular, with three primary teeth in 

 each valve, and transverse lateral teeth ; ligament on the 

 longest side. 



1. C. pidchra Suborbicular convex, smooth, slender; posteriorly trun- 

 cated ; one sharp-edged and two bifid teeth in each valve ; lateral teeth 

 plain and obtuse.— Cyclas pulcher, Sower. Min. Conch, t. Dxxvii. f. 1. — 

 Hampstead, Isle of Wight, Professor Sedgwick. 



TEREDINAD^. 



Gen. CXXXI. TEREDO. Ship Worm.— Shell orbicular, 

 hemispherical, equivalve ; hinge with a long curved tooth 

 in each valve, inserted under the margin ; ligament imper- 

 fect, the tube open at both extremities. Burrowing in 

 wood. 



* The ear-shaped process on the inside of' the valves, at the 

 outer angle under the hinge, having the inner margin de- 

 tached, and forming a straight transverse edge, and the out- 

 er margin much reflected. 



— 548. T. bipinnata. — Accessorial appendages long, linear, and 

 feathered ; an oblique rib on the margin above the teeth. 



Turt. Conch. Diet. 184, t. xi. £38, 39, 40.; Biv. Brit. 15 — In drifted 



timber, Exmouth. 



Diameter upwards of three quarters of an inch ; tube simple ; appendages 



about the tenth of an inch in diameter ; silvery white, with numerous pearly 



tubercles, the outer half with verticillate, lanceolate, fringed filaments — 



This is nearly allied to T. palmulatus of Lamarck. 



— 549- T. malleolus. — Accessorial appendages transverse and 

 mallet-shaped, with a slender point rising like a handle from 

 the middle. 



Turt. Biv. Brit. 255. t. 2. f. 19.— Drifted timber, Torbay. 

 Diameter about a quarter of an inch ; striae on the triangular processes re- 

 mote ; the tube consists of a slight testaceous deposit on the surface of the 

 chamber, the termination of which is slightly semiconcamerated. 



** The ear-shaped process with the inner margin on the in- 

 side furnished with a rib only, and not a detached margin, 

 and the outer edge is not reflected. 



550. T. navalis. — Accessorial appendages elongated and 



spoon-shaped. 



Linn. Syst. i. 1267 Penn. Brit. Zool. iv. 147- Mont. Test. Brit. 527. 



Home, Phil. Trans. 1820, 278. t. xii. f. 3. Turt. Biv. Brit. 14. t. ii. 

 f. 1, 2, 3 In timber exposed to the sea ; the scourge of shipping. 



